Granted, Han Chinese in the modern sense is a bit of a constructed identity (https://www.reddit.com/r/AskHistorians/comments/6e312e/is_th...), but it’s a construction that has held up in China.
With the exception of Guangdong and Hong Kong, you aren’t going to find many TV stations or newspapers that are carrying content in non-Mandarin Chinese. Yes, when I visit older family in the countryside, they may still speak their local dialect, but that is becoming increasingly rare: https://www.theatlantic.com/china/archive/2013/06/on-saving-....
Unlike in the US where African and French influences produced creole, and American pop culture has strong African and Latin influences, I don’t think minority group culture in China has anywhere near the same pull. Yes, they may trot out ethnic minority performers once a year during the CCTV New Year’s Gala, but you will not find “minority” singers charting on best seller lists, or “minority” actors in leading entertainment roles.
A 90%+ majority ethnic group is on par with what we see in Western Europe. Do Europeans see themselves as primarily multi-ethnic states? The self-description of a “melting pot” that is commonly used in the US, Canada, and even Central America don’t seem to be nearly as prevalent in Europe.