PeerTube resembles fedeproxy. More than mastodon because it does not deal just with conversations but uses ActivityPub for federation purposes.
A PeerTube server can follow other PeerTube servers and be notified whenever new videos become available. A fedeproxy server connects two software projects in the same way and one software project is notified when a commit shows in the other software project.
Here is the web interface PeerTube administrators can use to follow another PeerTube instance: