This is pretty much exactly why I vehemently disagree with Apple's decision to draw such a firm line in the sand preventing devs from accessing the eye/gaze data directly. I'm part of an academic spin-off start-up that specializes in analyzing gaze and movement data. Locking the gaze information outside of the app sandbox severely hampers the ability to quickly iterate design and UI patterns that could be game changing for accessibility. Hopefully they make accommodations moving forward for these circumstances.

The issue is doubly close to my heart because my father has ALS and is nearly at the point where eye-tracking will be his only means of communicating effectively with the world. While existing Tobii systems work well enough, typing with your eyes is still exhausting to do.

Ultimately I don't think a platform like the vision pro is suitable for ALS patients, especially later term. They cannot support the weight of the headset and/or fatigue will set in rapidly. Many (including my father) also require use of a ventilator, accompanied with a mask that can seal effectively enough to support the positive pressure necessary to inflate their lungs. Unless the form factor for HMD's minimalizes significantly, it will likely interfere with the respirator's efficacy.