Game Boy Zero with custom SD card reader game cartridge

I made a RetroPie handheld using a Raspberry Pi Zero and an original DMG01 Game Boy. I modified an original Game Boy cartridge to act as an SD card adaptor for the Pi, so I can have the same satisfaction of putting a cartridge in and powering it on like you would on a regular Game Boy. :) Some pictures of the build are here: Reddit thread with a bunch of Q, A: Feel free to ask any