> concept of ingroupness based on shared ethnicity, language and culture, in contrast of ingroupness based on shared commitment to universalist ideas like freedom, rule of law and democracy.

Is the latter not also nationalism, if you believe that those ideals create a group that is worthy of self-determination? Maybe it deserves its own qualifier, such as ideo-nationalism, to distinguish it from ethno-nationalism, but does the motivation fundamentally change what it is?

> OTOH, it is likely that the real reason why countries really work is because of some level of nationalism

I think you're probably right here. The question I have is if you can make that nationalism about something other than ethnic groups?