mumble does incredible VOIP. super minimal, pretty trivial to set up, and just works:tm: plus it has a lot of old school cool features since it's been around the game for decades. It's like discord but if it were old and cool.

Matrix i hear a lot of good things about, specifically the interoperability of it. That's pretty slick. One of these days i will get around to setting it up. Revolt exists, it's a discord clone, it can be self hosted, it's pretty fresh. Cool if you liked the 2015 era of discord i suppose.

I've used mirotalk for p2p screensharing, both the p2p and sfu version seem to be alright, the p2p version is significantly more performant in my experience though.