Google is adding audio group support for all the regular Chromecast. Anyone know if it's coming to Android TV's build-in Chromecast as well? I think we might get it at some point, as we also got the Google Assistant commands a little while ago, even though that was way later than the regular Chromecast, but maybe I'm just being too optimistic though...

https://blog.google/products/chromecast/five-reasons-and-two-colors-why-we-love-new-chromecast/