While good, Meta is likely to attempt to form a walled-garden in the vein of IOS and even Android to an extent. What I’d really hope for is a general-purpose computing platform with root access for the user, As I believe that mixed reality headsets have the potential to overtake both the smartphone and the PC as the default compute device of choice.

likely this. I fell for Apple once. I definitely won't fall for a Apple clone with one of the most untrustworthy companies since the turn of the century.

Is there any such solution in the VR space, even if not state-of-the-art?

There's SimulaVR. https://simulavr.com/

This seems like incredible hardware from apple, but I'm really hoping for root access to be more prevalent in the mixed-reality space. I really don't want to see another ios and android walled garden with so much creative potential on these devices, especially considering Meta seems to be taking the android position in the space.

it may serve in the same way the ipad / tablet adoption did - though this is more limited as it's single-user & ipads can be shared easily multi-user

I really