I mainly use Matrix for myself, my family, and have rooms set up for a community.
Discord I have and use as a couple groups of friends are still and basically every game dev uses Discord now and you have to go to Discord to find out any info about the game, look up tips/hints, or even report bugs. FUN!
Owncast Stream whatever you want on your own platform and announce natively to the Fediverse!
IDK why but tons of folks think it’s not feasible as they need million dollar computers. I’ve streamed to 70+ open streams, albeit as a test, on a like $5/month VPS. The key is that the resources needed are how many qualities you’re transcoding, not how many folks are viewing. Yes bandwidth is needed for each viewer, but that’s significantly less than people imagine.
Full transparency I run the [email protected] community, but I’m in no way affiliated with the project. I just love open platforms and open source.