Federation with Pleroma is currently broken, because Lemmy sends HTTP Signatures in a newer, incompatible format. This will be fixed in 0.17

I always get awaiting approval from pleroma ( Mastodon works like a charm on evrything other than sopuli) not sure if I’ve missed something.

Since Lemmy and Pleroma both support the ActivityPub standard, they can federate, and the servers will pass requests between each other. However, I expect it to be a similar experience to following Lemmy communities from Mastodon - you can follow and comment, but not much else, and it may be impractical. Pleroma does seem to have a “subject” field for messages, but I’m not sure it’s compatible with Lemmy (in fact, it seems equivalent to the content warnings on Mastodon.)