Chat for open source projects

It is difficult to find a good chat platform for an open source project. What are the attributes I am looking for?

- viewable without a login needed. This is the open in open source!
- supporting threaded conversations in a decent and usable way
- searchable log
- low resources desktop and mobile app, and equally capable web client
- support moderation for trolls
- preferably open source
- simple integrations to keep abreast of commits, issues and Ci/CD events
- preferably free, with option for commercial, paid-for support and hosting

The contenders are Discord, Slack, Matrix and Element, IRC, Zulip and a few more.

Discord and Slack are proprietary, but that is not the mostly disqualifying problem. Both required to be logged in making them not openly viewable. Discord web and Electron uses a huge amount of resources, and Slack threading is not usable at all. Slack free version has no history: after 10K messages or some time, the messages disappear unless you unlock a commercial plan.

IRC is (or was) awesome, but not something for the less trained casual user, and lacks history short of a bouncer and bots to log it.

Matrix and Element are great, but the Electron desktop client, like that from Discord is resource drag or worse. Its emphasis is on security, and while I like security, confidential and e2e encrypted messages are a decision factor for my use case.

To be continued....