>>11859603
Theres a thing called the "Game Boy Interface" (a replacement for the Game Boy player startup disc). It comes with a bunch of lookup tables that you might be able to use. I'm pretty sure BGB uses a similar approach for its color-accurate display mode.

Maybe-useful links:
https://www.gc-forever.com/wiki/index.php?title=Game_Boy_Interface/High-Fidelity_Edition
https://bgb.bircd.org/gbccolorlut.html
https://bgb.bircd.org/reality/index.html