So far I’ve explored Discord, Slack, Matrix, Mattermost, Rocket.Chat, Revolt, and Zulip. Annoyingly many of these are targeted at workplace communication which is not exactly the same as an open source project (especially around safety tooling!).
Someone had mentioned Nextcloud Talk and I get similar vibes (their materials focus on collaborating with your colleagues), but don’t want to completely rule it out. But also: what if we don’t want/need the rest of Nextcloud; can it be used standalone?