Yes, and there is a county in Wales called Monmouthshire, which for years had an ambiguous status. It used to be part of England, but it's part of Wales now. But there were many years when it wasn't clear whether it was in England or Wales. That was finally settled by a law in the early 1970s. But as recently as the 60s, officials were still arguing over it. The county council put up signs saying "Welcome to Wales", but they got painted over by people who were certain it was England.

https://en.wikipedia.org/wiki/Monmouthshire_(historic)

Yes, small countries are interesting. But I suspect they rely on their neighbours for most of their facilities. For example, surely the Vatican must get its electricity from Italy.

I agree, there will probably never be a one-world government. Definitely not with Russia the way it is. But even without Russia, the cultures around the world are too different. The United States is too big to be one country. They can't even all agree on things as important as abortion or guns. The US would be better off as a bunch of different countries. California, for example, could easily survive on its own.