If all federated communities could decide upon to regulate same rules, every one of them could be moderated by their own moderators. But the problem I see here is the things that’s being federated is in reality server itself which means it would be impossible(not sure but at least not necessary) to do such a thing. But anyone can easily build an app to collect posts from same communities, it does not require to play with activitypub, just lemmy api.

As a linux user, i always change my user agent. And i think many of the linux users also switch user agents so how correct is this data?

How does these stats being determined, just curiosity, i really dont know