The Nano IPS aren’t necessarily better than IPS, but it does have a better response time and a wider color gamut. The thing is, wide gamuts can contribute to oversaturation since most content isn’t really designed to be consumed through a monitor with those kinds of specs.
Nano IPS will give a significantly wider color gamut and a higher response time than typical IPS monitors. The color gamut is 98% DCI-P3 or 135% sRGB, which is almost as high as possible.
Nano IPS isn’t really better than OLED. OLED has better color contrast, similar color accuracy and consistency, and similar response rates. Nano IPS doesn’t have anything special to offer when compared to OLED, since OLED either trumps or matches Nano in most categories.