The public beta of tvOS 15 lets you try new features coming to Apple TV later this year, including 'Spatial Audio' with AirPods and HomePod mini pairing.
tvOS 15 public beta
After a closed beta intended for developers, Apple has released a public beta of tvOS 15 that anyone in the public can try. Just remember that it is beta software so you may encounter bugs.
tvOS 15 includes new features like Spatial Audio with AirPods Pro/Max, auto-detection of AirPods, HomePod mini paring with Apple TV 4K, SharePlay, HomeKit enhancements, and more features detailed in our previous article.
Also read: Review: Apple TV 4K 2021 (and tvOS 15)

Apple's new features for the home including Apple TV
How to get it
To install the tvOS 15 public beta you must first sign up for the public beta program on beta.apple.com, which will also give you access to iOS 15, iPadOS 15, macOS Monterey, and watchOS 8.
On your Apple TV box, go to Settings -> System -> Software Updates -> Get Beta Updates: On.
The finished version of tvOS 15 will be released this fall.