As long as the two services implement a shared protocol like ActivityPub [1], then yes they can communicate! For instance, both Mastodon and PeerTube (p2p youtube clone) implement ActivityPub, and so can communicate. And although according to [2], hubzilla doesn't appear to currently implement ActivityPub, however there is an intermediary "Bridgy Fed" [3] which can bridge between Mastodon and hubzilla.

[1] https://www.w3.org/TR/activitypub/ [2] https://activitypub.rocks/implementation-report/ [3] https://fed.brid.gy/