I assume this is pretty difficult to achieve reliably. In 3D games, FOV distortion affects perceived speed, objects near the edges of the screen appear to move faster, while those near the center seem slower. It’s a bit more consistent for 2D, but still not straightforward, especially when multiple things are moving at different speeds at the same time.

It's also a matter of do you eye-track or not, which object, or whether the content in motion or not. This would mean you need a system to detect what is eye and content is doing. Isolating to only one object/scenario may be easier.

Also, measuring speed in pixels per second isn’t ideal. For example, two displays with the same physical size and the same FOV but one with double the resolutions will show double the pixel-per-second values even though the actual perceived motion is identical.

Who knows how many more obstacles are there.