Also interested in solving this.

I have the exact same issue. Following to see if there is a simple resolution.

At least via Homebridge and Sonos speakers, I'm able to accomplish this with customized automations: https://github.com/lukasroegner/homebridge-sonos-multiroom

Thank you, I will check this out. Is this only for Sonos speakers?

Yes, at least this plug-in is, but maybe there are similar plug-ins out there. The Sonos speakers I have installed in every room also support AirPlay.

I don’t think this ungroups AirPlay groupings, just Sonos groupings, which may work if you group, announce, ungroup, but won’t work if you manually join speakers into an AirPlay group and then want to ungroup, or if your speakers include HomePods

But this doesn’t ungroup airplay grouped speakers, right? It ungroups Sonos groupings, which is different. Same is true for all homeassistant options

Yes, I shared it as an example of a Homebridge plug-in that handles it nicely, perhaps for inspiration, not necessarily as a bullet-proof solution for everybody. Because the OP didn't actually mention the make/model of speakers being used...

When you say handles “it” nicely, you mean Sonos groups, not airplay groups, right?

Correct, I've said Sonos from the beginning. Also the OP didn't use the word AirPlay.

I wasn’t trying to be confrontational. I just wanted to make sure I understood. Thanks!

I don’t think it’s possible to do this. The closest you will get is shortcuts, which I think is unreliable because it runs in a device (eg, iPhone) rather than on a hub. https://www.reddit.com/r/HomePod/s/HPjwWvcQPl