Display Maximum resolution propose

 human eye can see approx. 120 deg

https://en.wikipedia.org/wiki/Vision_span

and can move 120deg. so, human eye with fixed face can see 240deg.

also minimum pixel for human eye is approx 28sec.

https://webvision.med.utah.edu/book/part-viii-psychophysics-of-vision/visual-acuity/

Thus, for full experience for VR, we need approx 240deg * 60min/deg * ((60sec/min)/30sec) = 14400pixel.

Let's call "FullRetina resolution = (14K)^2".