Most of the possible contenders lack video calls and some also other needs mentioned by the OP. Nextcloud Talk has them all

Mind you that they keep paywalling previously free features. Example of them paywalling group calls and their Playbooks feature (v1 - generally available, v2 - in paid plans only): https://docs.mattermost.com/product-overview/mattermost-v10-changelog.html

Nextcloud Talk - actually free and fully-fledged unlike the alternatives that either require you to pay money or don’t support more advanced features like video calls

I’ve made a choice a while ago while deploying Nextcloud. Now I don’t care, as I trust myself that I have opted for something reasonable which was hopefully not SQLite