Demonyms
Then maybe we should make a point of renaming it to Ethnonyms? The trouble is that there's substantial overlap and it can also be quite difficult to determine. A person can be German by origin, but have a French passport. They might have even been born in France, and have some ancestors in Germany. We might agree that there are a French people (ethnonym), but were there a Yugoslavian people? Are all people born in Russia also Russians? Native Americans in the US or Canada?
I will go ahead and create Category:Ethnonyms.
I don't think things are so complicated. In my part of the world ethnicity is the most important organizing principle and is easily definable. ռուս (ṙus) / ру́сский (rússkij) are ethnic Russians, ռուսաստանցի (ṙusastancʻi) / россия́нин (rossijánin) are citizens of Russia. Yugoslavian and American are demonyms.