This repository contains 3D-printable models, PCB design files needed to make an arcade controller that looks like this:
This is a remix of the Flatbox Rev 5 by jfedor2 but with the added functionality of the recent update of the GP2040-CE firmware that now supports external devices that can authenticate the fightsticks and enable them to be used also on PS5 and Xbox Series X|S
The philosophy of this remix is to unify the auth addon and the controller itself without having anything sticking out from the side.
For the code you should still refer to the official GP2040-CE download page, I've used the Rev 5 Passthrough by TheTrain without having to configure anything else.