European Alternatives for Purchasing Domain Names?

Most of its TLDs are operated by American registry operators

It also uses AWS (Amazon) and even if you register through Gandi, the domain is ultimately managed under USA jurisdiction.

USA - Verisign (.com, .net)

USA - Public Interest Registry (.org)

USA - Neustar/GoDaddy Registry (.co, .biz)

So if you're trying to completely avoid US services with them, Good luck!

Edit:

Also most fonts, languages, website builders are also American. Not saying people shouldnt go with what you suggested just saying avoiding American services indirectly or directly is 100% impossible.