USB-C Charging (GBA SP)
The Game Boy Advance SP can support USB-C charging with nothing more than connecting the 5V USB power to the EXT2 port pins.
A simple carrier board can be created to hold a USB-C port, and connect the 5V rail to pin 2, and ground to ground.
Audio can also be routed if designed correctly to allow USB-C to 3.5mm headphone jack support.
Repairing USB-C Installs
A very common problem with installing the small USB-C carrier boards is the end user ripping traces and vias in the area. This is sometimes due to poor quality USB-C boards by makers, and sometimes due to poor soldering/install attempts.
Either way, watch how to repair them on our YouTube.
Here are some easy to solder points which you can solder to if you have torn the pins on the GBA SP PCB.
These pins are on the front side of the PCB right by the EXT2 port, and pin 5 (headphone detect) is over to the top left above D-Pad Up.
Simple solder to these points and directly to your USB-C board if you have ripped traces.