Two Nintendo Game Boy DMG-01 64x64x64 3D LUTs in HALD and CUBE format.

https://github.com/janvancoppenolle/LUT/tree/main/Retro%20GPU%20Conversion

The classic Game Boy could display 4 (2-bit) colours: black, white and 2 shades of grey. This conversion uses the Luminance (perceptual colour intensity) value. A pseudo-dithering trick is used to add 3 additional shades.
8-bit / 256-level greyscale ramp Game Boy 2-bit / 4-colour palette Pseudo-dither / 7-shade palette

Due to the interpolation when a 3D LUT is applied, there will be some additional grey pixel values present in the resulting image.
3D LUT CUBE applied in Photoshop

DMG-01 LCD Style

Nostalgic non-backlit Game Boy screen style bonus.