There's a client called SimpleX out there with some pretty cool technology in it. It can operate entirely in onion only mode and has a bunch of public channels for chatting and stuff.
The problem is the clients that exist for it are all really bad. Even the desktop client for Linux and stuff is all really clunky and missing basic UX features
The system for discovering channels is pretty miserable so far too, but there are bots to make it a bit easier I guess