Onion based federation is now working with #pleroma on #freedombone. This means that it's now possible to follow users on "onion only" installs.

This type of federation is quite significant, because it means independence from the DNS and CA systems. It means that even if you don't control your local internet router or don't have money to spend on domain names you can still create a social network. It significantly reduces the complexity barrier to entry for running a home server.