The big push is currently towards microLED displays because of the high brightness and fast modulation speed. Yield is not yet good, and there's difficulty in growing all colors on the same substrate. Picking and placing different color LEDs onto the same panel is not cost effective. Red microLEDs are also not yet as bright as blue and green.
There was a push towards micro liquid crystal panels with laser illumination to create holographic images with depth. There are several startups still pursuing that, but the image quality isn't very good at the moment.
The latest advancement has been in the optics with moving to pancake lenses to reduce the length of the optical path from the display to the eye. The Meta Quest 3 has a smaller form factor than previous generations because of this.