There are instances that federate together as a single sort of entity.
So, are there other entities? Meaning, is there a group of Lemmy instances somewhere outside of the existing ones we see here?
And, how do I get there, and which one don’t have people from the USA?
Edit, image example
You could host your own and decide for yourself with which you want to federate. Or just block whatever you don't like.
Easiest is probably to just subscribe to the communities you like and only browse the subscribed communities. And then block instances/users you don't want to see.
Only other thing I have seen is instances not federating at all. Lemmy and probably Piefed as well support that out of the box. In that case they are just normal forums.
Don't know any Lemmy server that does that but Truth Social is actually running Mastodon and not federating with the rest of the world. Not that anyone would want to federate with that shit show anyways.