Accessibility: controlling Android and typing via eyes

I have seen a video where a person with amyotrophic lateral sclerosis (ALS) could type on a screen using their eyes (the software used eye tracking software). But there are also many disabled people who are partially paralyzed or have handicaps where their limbs give away to spasms or have stiff or impaired parts (but can use their eyes). Wouldn't it be nice, if, all of these, could have some arm attached to their wheelchair or bed or chair or table, with Android on it, and could use their eyes to open up YouTube and key in some search videos, scroll, and watch YouTube or other media? Why doesn't Android offer this accessibility feature? Thanks.