This is a remix of a MD1 usb-c mod I found and used as a base.
SEGA Mega Drive MD1 Genesis 1 USB-c PD Board Power Mod
Uses HW-398 Black PD board with 9v-20v max 5a
I like these boards because they are 5V-20V, so they can be used for most consoles. it will snap into place and not move an inch. It is a very tight fit so that it does not move when in use.
To use as 5V, remove all connections / leave them all disconnected, and it will only ever do 5V.
You can either use it as 9V or 5V for the Mega Drive:
The author remixed this model.
modified most of the structure to fit a different board.