Apple, please provide access to face tracking blend shapes on vision os, just like you do on iOS. You have the best eye and face tracking implementation on the market, please let us use it. There is a sizable audience who will buy the headset just for it. I personally know multiple people who are not buying the headset simply because you locked those features out.
No raw camera access is needed, just abstracted blendshapes values. You will make the headset so much more useful if you do this simple thing.