My 10 year old iPhone 7 can play 1080p AV1 video in software for more than 200 minutes with VLC. The iPhone 7 was released a year and a half before AV1 was.
So I think it's a safe bet the current Apple TV devices are capable of playing AV1 video in software. There's a VLC release for Apple TV:
https://www.videolan.org/vlc/download-appletv.html
https://apps.apple.com/us/app/vlc-media-player/id650377962?p...
Not especially relevant, as the obvious use of AV1 on the AppleTV is streaming, and the OS frameworks don't request AV1 without hardware decoding. Services which provide their own video decoding (are there any?) don't seem interested providing their own software decoder for the ATV, despite the bandwidth savings.
Six years ago Apple TV added support for playing 4K YouTube video:
https://9to5mac.com/2020/06/22/tvos-14-brings-support-for-st...
YouTube's 4K videos are only available in VP9 and AV1.
So the YouTube app on tvOS has supported at least VP9 for six years and I wouldn't be surprised if it supports AV1 today.
Apple A17 Pro / A18 include AV1 hardware decode.
The latest Apple TV is on the A15:
https://en.wikipedia.org/wiki/Apple_TV_(device)#4K_(3rd_gene...
There may be a new Apple TV released this year.
> There may be a new Apple TV released this year.
The evergreen prediction in the Apple TV world :p. IIRC, Mark Gruman initially predicted the next model would be out H1 of 2024