This has been an idea for so long, and considering native Chromecast got it in Nov 2018, we're coming up on a year now. We still have had no word from Google when (or even if) this would become available, but there are so many of us out there that want it. The sound setups that I have for my TV's are the best sound setups in my house. It's a shame I cannot do this at this point. Anyone else agree? Sorry to only complain here..
i have to think of they wanted to do it, they already around have.
Cast built in on ATV is so far behind in capabilities, and despite 1.36.x being the minimum to get grouping which ATVs do .
Cast devices in general seem to be on their way out, the last bit missing would be an assistant TV dongle to replace the cc.
ATV is turning into cable boxes, and cable companies don't care about whole home audio. They do care about (casting) video apps though.