As some have noted, the previous Apple TV 4k already supports HDR10+ via tvOS 16.
For those wondering where HDR10+ content comes from: Amazon, one of the largest tech companies in the world. Some newer Android devices also shoot video in HDR10+. It's the only dynamic metadata format supported by Samsung TVs which...are the #1 best-selling TVS in the world.
Ironically, HDR10+ is "more open" than Dolby Vision but....for whatever reason, just about everyone supports Dolby Vision (Netflix, Apple TV+, Disney+) if they support a dynamic metadata HDR format and...the only streaming service I know of that supports HDR10+ is Amazon Prime Video. Lots of 4k Blurays support HDR10+, but that's not really relevant to discussion about a streaming box.
Having said all this...despite tvOS 16 supporting HDR10+ on the current Apple TV 4k...they (Amazon) still have not updated their app to support HDR10+. Source: I have Prime Video and the outgoing Apple TV 4k...the only way I can get HDR10+ on Amazon Prime Video is...by using the slugging app built into my TV. The Apple TV app still throws an HDR10 signal.