race and ethnicity are unscientific social constructs

Race and ethnicity are not the same thing. Ethnicity is very real and it’s defined by shared culture, shared history, shared beliefs, shared language, etc. Outward physical characteristics, like eye, hair, and skin color, can also be a part of ethnicity, but only a part and I think those things are less important than all of the other characteristics that define an ethnic group. It’s socially constructed, sure, but that doesn’t mean it isn’t real.

Race, on the other hand, is the idea that you can take those outward physical characteristics, group together arbitrarily all the people who share some or all them, and define these groups as racial subspecies of human. It’s nonsense, with absolutely no basis in what we understand about human genetics and taxonomy today. Humans are a very genetically homogeneous species. Despite our different outward appearances, we are all relatively genetically similar.

But that doesn’t mean our ethnic differences don’t matter. They do, inspite of our general genetic similarities. They matter because humans are very tribal, by our nature. We evolved to live in tightly bonded communities of like people.

You say that civic nationalism is ok but ethnic nationalism is not, but you can’t separate them. No civic system can be entirely culturally or ethnically impartial, and where there is ethnic diversity, the civic sphere will always be controlled by the dominant ethnic group. That’s why I advocate so strongly for ethnic independence, I don’t think any ethnic group should be dominated by another. I believe that every ethnic group, every nation of people deserves their autonomy and their independence.