The Sonos Home Theatre devices ‘bond’ to their surround speakers/sub to play all channels in sync and can be ‘grouped’ to play both TV and Music audio to other rooms - there is a slight delay (around 30-75ms) playing TV audio to a group, but that’s usually not too important if you are actually located in another room of the Home

Yes, if you’re in another room of the Home and the TV is playing through a Sonos HT device you can long-press on the Play/Pause button on a speaker in your room and it will join and pull-through the TV audio to that speaker without having to get out your phone. Note too that such things can often be done with voice commands if the speaker has a built-in voice assistant. I use 3rd-party Apps to do this and to even switch-on the TV and change its channels/inputs.

Yes, but it’s a setting you can also change in the Sonos App, called ‘TV Autoplay’ - if enabled, the TV audio takes control over the connected Sonos HT speaker to play the TV audio - if you disable the option, then it doesn’t and any music audio stays playing. Also note the integration with a voice Assistant service allows a user to switch between TV and Music audio with voice instructions too.

Just a question? Why use optical? An Android TV should have DMI-ARC, that would make it much easier to command the Beam through the TV remote (using the CEC protocol), and would possibly give less of a hassle when passing through sound from external sources.

My TV only has 3 HDMI outputs and I'd rather not sacrifice one for audio  output. Voice commands isn't really my thing

I understand. Most TV’s have four and I do think four is not very much either….