@revengeday@mircoxi I mean, there's quite a few different applications that use AP as a base protocol - "front ends" as you called them. Off the top of my head, I can think of
Misskey/Calckey/Firefish/IceShrimp
Akkoma
Pleroma
Pixelfed
Bookwyrm
PeerTube
Some of them are applications that are built for a specific genre or type of content, but they can all talk to each other. Plus there's multiple forks of Mastodon (Home Town and glitch-soc, which we run on CI). And there's a few more that are out there as well.