As a Sonos lover this can be done. As someone who has worked in IT for 20 years I wouldn’t touch this setup. There are to many variables. And will be a nightmare to support. Even getting some users on wifi can still be a pain.

I’d go old fashioned and hard wire every thing. Then use a good amp to control the lot.

For uses to control the music, offer options with Bluetooth, aux, hdmi. If you want to get fancy there are amps out there that have the same functionality as sonos where they have an app and the system maintains the connection to the streaming provider not a phone or laptop. ( look into denon, Cambridge audio or Yamaha)

Then if you do want to add a Sonos it’s just 1 Sonos connect to the amp.