Yes, our team uses it as a Skype/teams replacement, we pay $20 per month for a server on etke.cc in Germany. Their implementation, however, doesn’t seem to do group videocalls with screensharing, just group voice.

We are not federated because it is just an internal service that we need.

As far as I understand it, they kind of do but you need to install a third party app and use it through the Element interface. But I don't know for sure.

I have updated the list: https://sharedown.kaffekod.nu/05c3716c-05fd-46f0-a90d-efdc6ee8c8a4