No, you can’t add the Sonos Ones to your ‘home theater’ room, you’re already maxed out on the number of speakers that can be in that  ‘room’, although you could ‘group’ them with the normal 75ms delay and get a stereo signal from them. But having both ‘rooms’ in the same physical space might be difficult for you. 

It would be interesting to me to know what kind of signal your TV is sending to PLAYBAR, since it’s always possible the TV isn’t passing the full 5.1 signal that it’s receiving from your Apple TV. 

You may also want to look at both the speech enhancement FAQ and the night mode FAQ. 

@lancem631 Since the Playbar doesn’t support Dolby Atmos audio, set the Change Format setting on the Apple TV to ON and set Audio Format to Dolby Digital. And make sure the Sonos app displays “Dolby Digital 5.1” on the Now Playing screen when watching a 5.1 source.

Along with the Speech Enhancement and Night Sound features, lowering the Surround Audio level might also help you hear the dialog better.

No matter which Apple TV audio setting I use, Dolby Digital 5.1 or Immersive Audio Dolby Atmos, the Sonos app displays Stereo PCM.   Source: Sing 2 streaming Apple TV

Speech Enhancement enabled does indeed help.  Thank you, was not aware of setting.

You should be getting Dolby Digital 5.1 audio from Sing 2. Can you post photos of your TV’s current audio settings?

Ah, just discovered setting under TV Audio Sound Out - changed it to Auto and now am showing Dolby Digital 5.1 on Sonos App now playing screen.

Under the Sound Out Optical setting, is there an option for Digital Sound Out or DTV Audio Setting? 

With TV SOUND OUT - Optical Digital Out <Auto> now the Sonos app reports Dolby Digital 5.1