It works, sometimes but froze several times when I tried it with a meeting this morning. Once it is working well, it will be useful.
Turns out neither of my AppleTVs are gen2. So, we are SOL for the time being. It still works for me to join a webinar with AirPlay.Based on my testing, you will need to connect your iPhone to your Apple TV via continuity in order to progress past the startup screen on zoom. However, once you are inside, it appears possible to then disconnect your phone and still stay in the zoom session.
Do be careful not to click on either the unmute or video off icon, else, it will bring you to another screen prompting you to connect your iPhone camera again. This thing is seriously calling for either an Apple TV with an inbuilt webcam, or the ability to connect a separate website.