Had the US lost its independence war, could it, Canada, Australia, and NZ

The U.S was a backwater for the first century of its history. When WWI began, Great Britain was responsible for 75% of maritime trade.
They have little incentive to be on equal terms with technologically inferior countries. If London were the capital, they would just treat the other English speaking lands as second class citizens. War had to be fought so that the U.S has it's own capital. There would be a risk of punitive taxes against Australia and New Zealand if the capital is in D.C or Philadelphia. Lastly, Great Britain would feel threatened by such a powerful competitor, thus be strongly opposed to such a union. In addition to a naval advantage, Great Britain would be poised to dominate Oceania since the population of cities like Melbourne were booming with British migration while most of the western half of the U.S was still rural. Even today, much of the northwestern U.S has yet to be colonized in large numbers.

Although, if in 1774 Canada were to be more receptive to the first continental congress, history would turn out a lot differently. If the U.S and Canada became a single country, Great Britain would then focus on Oceania. Australia, New Zealand, and Singapore would have a lot more British than today. Australia and New Zealand would have more cities and a larger GDP. Philippines, Papua New Guinea, and Indonesia might become important British colonies. Trade with India and China would become more important as well. Great Britain might colonize China to the extent it colonized India otl. India might become an even more integrated part of Great Britain. Madagascar might get colonized by Great Britain.

Alternatively, Napoleon conquers Europe, and the United Kingdom becomes a second rate power. England still has the industrial revolution going for it though. Even Napoleon can't reverse the discovery of the steam engine. He can however poach or prevent the invention of the power loom and spinning Jenny. Relatedly, the English economic advantage gained by the cotton gin would become a lot more precarious. Micheal Faraday would likely not have the leisure to make discoveries in electricity. France being the strongest country in the world atl, would bully and steal England's technology, causing it develop little of its own. Thus, global technological progress would be slower with a 1774 continental congress PoD causing a Napoleonic victory. That's not to say a Napoleonic victory is certain, but it's a distinct possibility.

Former Spainish colonies might become separate countries even faster with a Napoleonic victory. France might invade/retake Canada and the Louisiana territory. If the later fails, the former will be accelerated. Otherwise, there may be a latin American Union that otl independence. Not sure what would be the fate of China, India, and Oceania with a Napoleonic victory. Less British influence, to say the least. China might actually become more powerful or at least remain more independent. France is unlikely to develop as strong of maritime trade as otl Great Britain. They'd tend to work with foreign powers, but be less inclined to dominate them. The French would rely more on forts, but less on colonization or at least the colonization would be more spread out. Great Britain tended to have a strong core which slowly expanded outward. In contrast, France preferred to claim as much land as soon as possible, before there was really the manpower to make good on that claim. However, with a Napoleonic victory, this pattern could change.

France would inherit the Dutch East Indies if Napoleon is victorious. Which would provide a strong incentive to completely shut Great Britain out of Oceania. There could be a scramble for Australia, in which both France and Great Britain colonize Australia. More likely however, citizens from both countries would just prefer to migrate to North America like otl. Latin America could also be part of a scramble for Australia. The Mexican American war would never happen. Either France wedges itself between Spain and the U.S, France causes (directly or indirectly) the Mexican revolution to occur earlier, or Latin America is significantly more powerful atl. The latter is consistent with a scramble for Australia timeline. Then again, can Spanish speaking America even remain united without Spain? The Hispanic empire is unlikely to have the sort of cohesion as the U.S. There could be three or four great latin powers. France would likely promote this as a counterweight to a mega U.S. If somehow latin America can remain united (with Mexico City as the capital?) then they would be quite powerful. Perhaps even more powerful than the English speaking North American Union. France would be able to tip the scale in favor of one over the other, regardless of whether they regain Quebec and the Louisiana territory.

South Africa would also be part of France. France might take a greater interest in Africa earlier than otl. Disease ridden tropical climates are likely to be avoided though. At some point, there's likely to be decline. The only force that would prevent decline is a great rival. This can come in the form of the North American Union or the Latin American Union. Great Britain is unlikely to offer much resistance unless it allies itself with America. Even then, they're likely to get the worst of such an encounter. While the Americas are a vast land that would essentially be a wild goose chase for France to dominate in a single campaign, England would comparatively be a much more fruitful conquest in the short term. Lastly, with a greater focus on continental trade as opposed to maritime trade, Japan is unlikely to be "open upped." It is possible though at some point Japan is willing to trade with France though. China and India are likely to have European trade ports, but less wars with the west. Subsequently, Europe makes less inroads into their interior. However, steam power would give France a distinct global advantage. Eventually, the west would dominate the east. It would just take longer. One possibility is that France adopts a corporate structure similar to otl U.S instead of the colonial system or something inbetween.

Instead of French corporations in countries like China and India, France might want to promote stability in foreign countries to promote trade. This could result in foreign countries developing the steam engine and other technologies which prevent invasion by western powers. The Ottoman empire could become more powerful atl. Although, France is likely to dominate Egypt and the Suez. Trying to completely dominate the Ottoman empire would cause France to overextend themselves and lead to their downfall. Simply sacking the Ottoman capitol from time to time would be sufficient. There could be a major disease outbreak impairing victory, much like what often occurred when Rome sacked the Persian capitol. Speaking of diseases, there would likely be slower progress in terms of medical advances. Uncompetitive monopolies would predominate, leading to less technological innovation. Evenstill, a Napoleonic victory would not reverse the invention of the cotton gin and the steam engine. Railroads would certainly be invented. There could be even more ambitious infrastructure projects atl. This would however lead to less maritime trade. The cotton gin however would greatly increase maritime trade. Unless France opts to grow more cotton in the mediterranean, reducing trade in the Atlantic. Cotton could also provide more incentive for France to invade south eastern North America. The Caribbean would be colonized for this reason, in addition to being of militarily strategic importance. Sugar would be another major reason to colonize islands is the Gulf of Mexico and Caribbean. Haiti would be much more prosperous atl. As would the rest of the islands.

Depending on how competitive mediterranean cotton is to American, slavery will be less common. There will be some of it, but existing labor in the mediterranean would be sufficient to provide much of the cotton for Europeans. However, if the labor is significantly cheaper in America, then slavery may persist for a longer period than otl. That is if the cost saved in labor is cheaper than increased transportation costs, slavery will flourish. America was more maleable in terms of economics because there were less powerful entrenched interests preventing change. Which does tip the scale in favor of slavery. The more fertile and underdeveloped the land, the more likely slavery will flourish. The timeline for slavery overall might be more like otl Brazil. Inevitably, the market will become mature. Technology will progress. Slavery will become obsolete. Not that low wage urban jobs made possible by the steam engine were much better. The line between the scramble for Africa and slavery would be even more blurred than otl. Not that the "scramble for Africa" would exist, since there wouldn't be competing European nation states. There would just be the one great continental power connecting railroads throughout Asia, Africa, and America.

Considering iron was the initial economic impetus for the steam engine in the first place, the Eiffel Tower is perhaps the greatest symbol of an industrial France. There would likely be many skyscrapers. The automobile would likely be invented as well. Although, since England led the industrial revolution otl, innovations would likely be much slower. England was essentially forced to rely on coal after they lost the U.S. An all powerful France would not have such a sense of urgency. They would likely become lazy. Still, once the cat is out of the bag, technological progress will trickle in. Rivalry from the North American Union or the Latin American Union can speed up the process. The Ottoman Empire is likely to be crushed instead of being a rival though. There simply wouldn't be enough of a buffer zone. Consequently, hostilities would become militaristic instead of economic. China and India could potentially become significant economic rivals which encourage France to out compete with them through technological advance. Butterflies could even cause Japan to become a significant economic rival in the 19th century. Suppose France were to promote a strong Korea. This is yet another possible angle. Regardless of the specific route France takes, it seems like France will be less domineering to colonies than Great Britain was. They might not even have colonies at all. Rather just one great big incorporated empire.