Aside from the skepticality of the proposed product & business idea, on the technical side there is tremendous value from accessible, robust and portable eye tracking. During my undergrad I was fortunate enough to work at a neuroscience lab where we built a 3D Unity game interfaced with a joystick, ECoG, and eye tracker to study attention and learning. If nothing has changed, Tobii is still the global leader in eye tracking hardware [1]. They have a wide ranging of products to choose from depending on your budget.

[1] https://www.tobii.com/