I tried all the configs and it looked good, great work!
Could you please explain how to get the green colors for the Gameboy? I placed the palette folder with the “default.pal” file into /home/pi/RetroPie/BIOS but I guess there is more to it.
I also noticed a diagonal “/” line in the GBC overlay when playing the gbc super mario game. It was only seen in that game by the few I tested. The right side of the / was darker and the left brighter. It was fading away the more I lowered the input_overlay_opacity.