The community !lemmy411@lemmy.ca was created to help people find other communities on Lemmy and Piefed, there hasn't been a post there for a while now.
As for what you're looking for, I don't think there are any Lemmy communities with voice chat focus. There are text threads where people ask how everyone's doing or what their weekend plans are, etc., you can ask a question like that in various spots like !vancouver@lemmy.ca, !canada@lemmy.ca, !casualconversation@piefed.social, !general@lemmy.world
I would suggest looking for Matrix servers and channels to join that do casual voice chat. You can follow this link to see instructions, once you are signed into Matrix, on how to access a directory of public channels on various topics.