The EU flag is technically also the flag of the Council of Europe, of which Switzerland and Co are members. The only European countries not in the CoE are Belarus and the Vatican though Russia's membership is suspended.
I suggest my drawing of Europe by memory. Your favourite country might not even be in there but it's simple so you can see it as a small icon! I see no downsides.
While it may not nominally include them, the flags stars represent the coming together of countries. Stars ate no longer added to represent individual countries as theynjoin, so i thinknit still fits.
Using the map works but as a circular icon it will also exclude countries or be too small, so it doesn't fix the problem presented.
Its not ideal as a logo but unless a better option presents, I'd keep itnover a map. Unfortunately, this specific map is not loading for me. Possibly an update issue.
Unrelated, but that map is a little bit funny. Eastern Latvia apparently seceded, Ireland reunited and there's a big lake between Romania and Bulgaria.