ActivityPub is a very loose spec, and obviously it doesn't just magically work across random services. You would have to implement support for the specific type

ActivityPub is a very loose spec, and obviously it doesn't just magically work across random services. You would have to implement support for the specific types of notifications for them to be meaningful. An example of this is PeerTube federation with Mastdon as seen here https://peertube.cpy.re/videos/watch/da2b08d4-a242-4170-b32a-4ec8cbdca701 https://peertube.cpy.re/videos/watch/da2b08d4-a242-4170-b32a... For example, GitLab projects could publish their activity feed to Mastdon. You could follow it to see what commits they make, issue discussions, and so on. Meanwhile, federating things like pull requests would happen across Git based services. So, if Gogs decides to implement compatible ActivityPub protocol, then it could integrate into the federation of GitLab servers.