I played around with this a bit. Doesn’t work amazing on my iPhone model (SE 3rd gen), but it’s pretty cool. I don’t think there’s an API to use it in apps yet, but I would love to make an eye controlled mobile game.
I know of at least 1! “Before your eyes” though i played it on a PC with a webcam, and I believe the mobile version is only available for Netflix subscribers, but I would strongly recommend it! It has a well told story with an very unique means of interaction
https://www.beforeyoureyesgame.com