Fwiw HorizonOS does support hand tracking (at least in the Quest 3 which I have) and you can navigate the UI without controllers. It works quite well.
The Quest Pro also supports eye tracking, though not sure how well-integrated that is into the experience. I believe it's used to achieve foveated rendering with steam link, though.
Yup and the Quest 2 and even the Quest 1 got it too! Though the Quest 1 is a bit behind the latest improvements though since it no longer receives OS updates.
The Quest Pro also supports eye tracking, though not sure how well-integrated that is into the experience. I believe it's used to achieve foveated rendering with steam link, though.