Federation with the Matrix Protocol
I know there are already a lot of requests for federation. This is a different type of request though, as it is more specific:
Similar to how true email federation uses open source federated protocols like IMAP, SMTP, POP3, true federated banquet style chat applications should also use open source federated protocols to allow other clients & hosts.
The Matrix protocol (which is managed by a non-profit organization) is the most popular way to do this. I would love if Microsoft Teams added support for this to allow it to truly replace email, and communicate with customers, vendors, etc. that may not have Microsoft Teams.