I haven’t had good experienced getting HomePods to play well from a Mac. They do alright enough from my phone or AppleTV but they’re much less reliable than 3rd party Airplay2 speakers like the Kef LS 50 Wireless II I have upstairs. I swear the next time I get an audio drop or stutter from them or an infinite beach ball trying to press play in Spotify Mac, I’m retiring them to “set timer” only duty and buying something else, maybe the desktop speakers from KEF or whatever looks good on audiosciencereview.com for desk form factor

Airplay2 to my Apple TV and from the TV through to a “dumb” receiver and speakers works great, I would highly suggest that route for your main system. For me it’s the right balance between “just works” convenience and audiophile sound quality.

I was going to do the same thing.

I posted elsewhere on this thread how the third party app Clic for Sonos has saved me. Might be worth a try before you go through the expense of changing over.

Apple forces you to use Apple Music though :/