Updated: Mar 11, 2021
Although there was no need for me to do so as my charging port worked, I converted my Gameboy Micro to USB C. In 2021 I'm on a mission to USB C everything.
Pre warning: I do this as a hobby. I'm not Nintendo. I'm not an electrical engineer. If you break anything it's not my fault.
What you need:
Soldering iron + solder
6 pin female USB C