We did a lot of live scheduled chats back in the 2000's. There was a chat popup similar to Messenger and mods would be there with the same powers to boot the occasional troublemakers.
Our most recent AMA was in 2017 sponsored by Sony with guest Joel Silver.
I set Joel up with an account & head shot avatar with enough privileges to include links and such. The users really enjoyed it. At the end we gave away a Sony 4K Ultra HD Blu-ray Player.