Found the list of things that work and don't work yet:

https://git.jami.net/savoirfairelinux/ring-project/wikis/fea...

Looks like the traditionally hard ones "Group chat" and "Chat history shared across devices" are still in the making.

I wish best success; I find that a reliable, safe, featureful, cross-platform, high-quality instant messenger is very much needed.