There's quite a few Lemmy apps out there - Jerboa is the official one I believe, but probably the one I use the least. Liftoff, Connect and Thunder are my favourites, without picking one in particular.
I really don't use anything outside of Play except in extreme circumstances, and certainly not for anything social.
It's generally a bit of a faff I can do without. I used to use custom ROMs and all that for certain things but I try to keep it simple now if possible.
I used to have custom ROMs on my phone. It was a good learning experience and I got a fair bit of enjoyment out of it but I don't have the time now, either.
I did it for privacy and performance purposes but I gather that we are screwed in terms of privacy by using any android phone, nowadays.