That’s an interesting question!
When I started making the Yurivania series I wasn’t very familiar with the GB line of hardware so I didn’t really understand the implications of my color choices.
Instead, I thought of the values that the default web emulator GB Studio uses as the target palette. It attempts to desaturate the colors like a non-backlit GBC, but I don’t believe they do a terribly accurate job.
In general, anything slightly desaturated will work, but you can use the screen shots on this page as a guide!