It's among top 2 FOSS lemmy android apps in my opinion. Thunder is if not smoother as smooth as Sync but it lacks some polish, LiftOff is definitely designed with fediverse in mind thus has very interesting functions, Jerboa is basically Boost UI wise, missing a lot on the functionality front, Infinity, however it was the last time you checked it out on alien site except bugs related to API differences. And yes I keep shuffling between all of them and then some.
Edit: Connect is not FOSS as of yet. Though If I'm not mistaken dev is planning on open sourcing it in the future. Thanks to the commenter in another thread for reminding me.
Of course there is a KDE app that is feature packed and beautiful and no live being has heard or known about.