The PCB finish is ENIG.
GBxCart firmware updates
For GBxCart v1.4, it keeps all existing functions as there is lots of firmware space available. You will need firmware R39+L8 or higher (use FlashGBX to update).
Games that don’t work
Judgement Silversword – requires 2Mbit (256KByte) of SRAM according to an emulator
Video of a quick prototype below