I'm fairly certain it isn't, at least in the core engine. The dev team works really hard to make sure every feature going into core is:
useful for many/most users
impossible to create otherwise
has significant community demand.
Things like eye tracking are more likely to be done in add-ons, GDExtension, and the like. You'd have better luck looking for an addon or C++ library that could get integrated
I would like to get the eye tracking information from a quest pro. I think it would be better for navigating ui in VR and I want to make a wizard game where spells go where you're looking or lock on to what you're looking at.
For starters, cameras are only supported on iOS/macOS as far as I know. Someone wrote a python script to do face tracking and send the information to Godot via TCP a while back, maybe you could take inspiration from this?
I was talking to some people from a company that makes an eye-tracking thing and apparently it's really hard to do with precision, so it's unlikely that any hardware you're willing to pay for is going to do what you want.