[Quoth]

Nxtpaper is a layer and surface treatment. It's on OLED and LCD and doesn't affect the gamut. OLED isn't inherently better. The Apple iPad pro looks rubbish in comparison.

The "paper" modes are silly marketing that reduces the quality.

OLED is using electroluminescent dots with phosphors. They age more than LCD and inferior to actual LEDs (which are rare as displays).

QLED is LCD with green and red quantum dots that use blue light. They work differently to phosphors. So QLED uses an efficient blue LED backlight. Regular LCD uses a dye filter and these vary in quality.

EDIT:
You only need wide gamut RGB to edit for printing colour Art books, or commercial movies. Any tablet or phone is literally many thousands of times better than Kaleido eink and some nearly a thousand times better than Gallery.