I think the most spiritually correct solution would be to use PeerTube considering that it’s also a federated system and therefore can interact nicely with Lemmy.
Every user, post, community, etc. on each of these services is represented as an ActivityPub object. Let’s take the example of following your Lemmy user from Mastodon. I can search for @Gohos in Mastodon and in the background my Mastodon instance will issue the following WebFinger request to lemmy.ml: lemmy.ml/.well-known/webfinger?resource=acct:Goho…. This will return the following JSON: -
This includes two important properties: inbox and outbox. Using ActivityPub I now know I can send you a message by POSTing a request to your inbox and I can fetch posts, comments, etc. you’ve made via your outbox.
Your public key is also included. This is how, if you sent me a message, I can verify that the message actually came from you.
That’s a very brief overview but I hope that helps!