Yes, the microLEDs (I've heard of) are InGaN on Sapphire which are diced and placed in arrays. Apple bought a company doing this several years ago, but the dens

Yes, the microLEDs (I've heard of) are InGaN on Sapphire which are diced and placed in arrays. Apple bought a company doing this several years ago, but the densities they are capable of (30-100um pitch) and yields (1dppm?) are not a match for head mounted 8k displays (100mm/8000 = 12um pixel =>6um subpixel). There are microOLED manufacturers like eMagin which integrate the active matrix into a Si substrate and use a color filter over white OLED, but even they are limited to ~2k RGB (per eye) at 9um pitch.