I just joined Lemmy and I have already seen a comment from a tankie telling all Americans to "rot and die" in this same community. So no, it's not all wholesome.
Probably. It's one of the instances dedicated to Marxist-Leninists. I block some communities there due to not wanting to deal with apologia for what I see as crimes against humanity but, there are also meme communities, etc. Also, despite significant differences, the user interactions that I've had have been much less vitriolic than other parts of the Internet.
If it helps, it only ever seems to be the tankies, which are progressively becoming the minority. I'm sure more dicks will show up in future waves, maybe, but...I'm kinda seeing the point of just the lowest possible entry hurdles.
Actually, hold on, tumblr was talking about ActivityPub a few months ago, so if they ever actually do that and do it functionally, that will change the culture pretty substantially. Much more weeb/sociopolitical. I'm happily fucking out of the politics here by choice.