anarchist and general libertarian socialism on lemmy

Probably, though you may have to dig to find them. Lemmy is rapidly becoming like Reddit in that if something exists, there is probably a community for it. If your local search doesn't bring anything up, I would check on lemmyverse.net. It seems to have indexed most if not all of the current communities. A quick search just now for "liberta" pulled up roughly 10 communities.

There are definitely communities on Lemmy.ml, have a look using Lemmyverse

Not super active but maybe you can help kickstart it! [email protected]