Apple's tvOS 15 is now available for Apple TV
The newly updated tvOS 15 has just been released, bringing with it the usual slate of bug fixes, as well as a few new features, some of which had been disclosed during Apple's June WWDC event.

Among the new updates include several geared toward improving the audio experience of those using an Apple TV. For example, those with AirPods Pro and AirPods Max will now be able to listen to Spacial Audio, a system that uses gyroscopes and other sensors in the devices to simulate 3-D listening.

A new dialog also appears on the Apple TV if a user's AirPods are nearby. The feature is similar to how it currently works on macOS. Users can pair their AirPods with a press of the TV button or dismiss the dialog by tapping the back button.
The new tvOS also received a few new HomeKit features. While tvOS 14 bought HomeKit to Apple TV, tvOS 15 allows users to view HomeKit-compatible security cameras in a grid view. Users can access this view from the Control Center or the fullscreen camera view.
A few other minor updates have also been added. Users can now use their iOS or iPadOS devices to sign into tvOS along with Touch ID or Face ID.
Users can also use Touch ID or Face ID to authenticate purchases and sign into compatible apps.
Lastly, just like in iOS 14 where users could use the original HomePod as default audio and control, users can now connect the HomePod mini for control of their Apple TV and be used as a default audio source. For example, asking Siri to put on a TV show will turn on the Apple TV, turn on the TV, and change the input to Apple TV.
Unfortunately, as learned earlier, SharePlay would not be debuting at Apple's September event. When released, SharePlay will be a feature that allows users to share media during FaceTime calls. Users can watch movies, listen to music, or see someone's screen with all callers in perfect sync while using SharePlay.
Read on AppleInsider

Among the new updates include several geared toward improving the audio experience of those using an Apple TV. For example, those with AirPods Pro and AirPods Max will now be able to listen to Spacial Audio, a system that uses gyroscopes and other sensors in the devices to simulate 3-D listening.

A new dialog also appears on the Apple TV if a user's AirPods are nearby. The feature is similar to how it currently works on macOS. Users can pair their AirPods with a press of the TV button or dismiss the dialog by tapping the back button.
The new tvOS also received a few new HomeKit features. While tvOS 14 bought HomeKit to Apple TV, tvOS 15 allows users to view HomeKit-compatible security cameras in a grid view. Users can access this view from the Control Center or the fullscreen camera view.
A few other minor updates have also been added. Users can now use their iOS or iPadOS devices to sign into tvOS along with Touch ID or Face ID.
Users can also use Touch ID or Face ID to authenticate purchases and sign into compatible apps.
Lastly, just like in iOS 14 where users could use the original HomePod as default audio and control, users can now connect the HomePod mini for control of their Apple TV and be used as a default audio source. For example, asking Siri to put on a TV show will turn on the Apple TV, turn on the TV, and change the input to Apple TV.
Unfortunately, as learned earlier, SharePlay would not be debuting at Apple's September event. When released, SharePlay will be a feature that allows users to share media during FaceTime calls. Users can watch movies, listen to music, or see someone's screen with all callers in perfect sync while using SharePlay.
Read on AppleInsider

Comments
And, any app, not just the TV app.
What I'm trying to say is that Apple, as we sometimes see, is not necessarly first to implement something, but they really do try to be the company which implements a feature in the best possible way. If you look at the old Xbox service again, it's not like you would use the Xbox "Live Party" mode on a Zune, Windows PC and Xbox simultaneously. As far as I know, it was only something they tried on the Xbox itself - not cross-platform.
Disclaimer: I'm an XBOX One owner, Apple enthusiast and old-school Linux user, so I have all kinds of devices. Writing this comment on the M1 Mac Mini in Monterey beta.
Hopefully they'll wait for me to initiate the installation this time. I generally like to wait a few days -esp. with original HPs that can't be easily replaced- and have toggled the settings to allow me to do that. The last few software updates, however, have gone through automatically anyway, which is not ideal.