I worked on eye tracking hardware for Microsoft HoloLens. Several AR headsets offer decent eye tracking, including Hololens 2 and Magic Leap's ML2. I think Tobii's eye tracking glasses are probably better as a stand-alone solution though: https://www.tobii.com/products/eye-trackers/wearables/tobii-...
Agreed, the eye tracking itself is really a mostly-solved problem (Tobii are indeed leaders in the area). It's how it's used that matters - and as mentioned above, it's likely that it's the usability/interface that needs work.
PS VR2 uses Tobii's tech to do eye tracking, it is mostly being used for foveated rendering but some games also use it for gameplay, one for example allows you to shoot at enemies with your gaze.
Not sure, but it would be cool to do something that didn’t require cameras, like EMG to detect eye motion from muscle activation. It would be hard to get the necessary accuracy though.
I don’t know about the Tobii glasses, but I have a Tobii head/eye tracker that attaches to my monitor, and it works incredibly well and was only $200 or so. I’d be surprised if this isn’t an essentially solved problem at this point.