Inclusive Technology has debuted the Skyle, a housing for the larger iPad Pro 2018 variant that allows this tablet to be operated using eye-movements alone. It can allow certain users to access the App Store independently for the first time, while also integrating with other personal or household devices that have infra-red (IR) receivers.
https://www.notebookcheck.net/Control-your-iPad-Pro-12-9-via-eye-tracking-alone-with-this-new-accessory.452248.0.html
Rather too expensive considering that Tobii Eye Tracker sells for 169 EUR.