I am pretty much firmly in the camp of Walker Connor in noting that nation is not a synonym for state and that there are few actual nation-states in the world. Rather a nation by definition has an ethnic basis. A nation-state is a state that provides political self determination to a single dominant ethnic group. Not every independent political state is thus a nation-state. In fact the vast majority are not. Japan is a nation-state, Germany is a nation-state, France is a nation-state, but most states in Africa are multi-ethnic and do not correspond to a single dominant ethno-nation. Hence they are not nation-states, but rather states with multiple nations living in them. The fact that people identify strongly with these multi-ethnic states does not make them nation-states. State patriotism and national identification are two very different things. Which is why people still say they are Asante, Ga, Ewe, etc. in addition to being Ghanaian. These smaller groups are the ones that correspond to the idea of nation in the sense of being German, French, or Japanese. But, of course confusing statehood and nationality which Connor has rallied against for decades is nothing new. It has dominated a lot of badly thought out argumentation for decades. In the former USSR citizenship is and has been since the 1920s separate from natsionalnost.
In the USSR everybody had a single Soviet citizenship which under the Soviet constitution was theoretically equal for everybody. However, in reality a host of rights and privileges were determined by line five which designated natsionalnost.
Soviet was never an option for line five. One could be Russian, Ukrainian, Jewish, Uzbek, German, Tatar, Korean, Armenian, Karachai, Georgian or a member of any number of ethnically defined nationalities, but one could never say their natsionalnost
was Soviet. Likewise the United Kingdom of Great Britain and Northern Ireland is not now and has never been a nation. It like the USSR is a union of several nations. In this case it is specifically a union of the nations of England, Scotland, Wales, and Northern Ireland. There is no British nation-state. There is a British state and English, Scottish, Welsh, and Irish nations. Often when dealing with the political entities drawn on maps we are looking at states that do not correspond to ethno-nations and are hence not nation-states.