I used Infinity when I was on Android. The developer said that he’s gotta job-hunt (as someone pointed out, the fact that people prefer the app written by a single person who is now looking for a junior developer job over the official one that Reddit had a whole team to work on is a bit embarrassing) and doesn’t have plans to add Fediverse support, but also that it’s open source.

https://github.com/Docile-Alligator/Infinity-For-Reddit

I imagine that if someone wants to do so badly enough, they could add Fediverse support.