I am working on fedi software that is hoping to allow Kodi, Plex and Popcorn Time get rid of IMDb/TMDB dependency. Dm me if you're skilled in SvelteKit and/or Go, especially the Fiber framework, or machine learning with Rust and willing to contribute.
Zulip is really neat. Telegram is easy to set up and has a native desktop client and scales well. Self-hosted XMPP is nice, as as the name says, it's extensible. Mumble has a mid interface but great performance and privacy.