The controller app does not actually play music, so your premise that an Apple TV controller will change anything is fatally flawed. It would solve no issue regarding audio transports.

There is a 3rd party Sonos app for the ATV which looks very pretty, but has never worked on my system.

It isn’t flawed.. I could turn music on/off using the appletv instead of phone or computer.  Then I could make/receive phone calls without music interruptions.  Also take my laptop to work and my sonos could continue to play uninterrupted.   Using Airplay means I must have the device with the music connected to the sonos.  If Appletv has its own app then I could play music and TV seamless with no interruptions.   I can receive calls/facetime and zoom meetings on the computer and calls on the Iphone with the hassle of changing the audio back to phone to answer a call.    Is it fatally flawed? Nope.. Its no different than when amazon didn’t have an app on appletv.  You would just play it on the phone or computer then airplay to the appletv.   Now that amazonprime  and amazonmusic are on the Appletv there is no need to airplay to it.  amazonprime / amazonmusic don’t have music or movies in the apps. They are just controllers as well.    Why download a third party app when Sonos already have two apps.. macOS and iOS. I’m just asking for them to open the doors more and have a tvOS compatible version as well.  Exactly what amazon did.  They had both macOS and iOS versions then developed a tvOS version.    

I find it weird that they haven't taken the iOS app and repackaged it for tvos.  It seems like 95 per cent of the work is already done.

I totally agree.  Then the great features like radio and playlist can be played from the appetv.  

LOL spoken like a non-developer. All of the UX needs a complete do-over, as it was designed for touch input, not the dumb-ass controller that ATV uses.

I’ll stand both corrected and chastised and instead say that I find it weird that a company who charges a premium price for a product designed to be in a home theatre setting doesn’t offer a controller for one of the primary home theatre streaming platforms.

Better?  ;)

I’ll bring this back up.. Sonos has both an iOS and macOS controllers.   Sonos also has airplay with Apple.  So why can’t they do some work providing an app in tvOS for apple tv??   Especially since Apple is selling Sonos products on its webpage and in the Apple stores. If they don’t know how can’t they just ask Apple for assistance. It’s a win win for both companies.