The Gameboy Modding scene has been popping off for decades now. There are many cool custom builds that can be done. While most mods are purely for ascetics. Display mods feel nearly mandatory for most to enjoy these classic consoles in the modern age. 
Vertical Line Fix
Backlight Installation
Bivert Chip Installation
As of now, there are IPS screen mods for GB / GBC / GBA!
These screens are backlit and look amazing. 
DMG IPS Screen Install
(Coming soon)
GBC IPS Screen Install
(Coming Soon)
GBA IPS Screen Install
(Coming Soon)