Issues with Stick Emulation

[D-tech-pro]

Is it possible to modify the code to use pins to receive joystick input for emulation? I would like to take a Pico and make it the heart of a custom controller and I'm so close except I cant figure out how to modify the code to use actual 2 axis joysticks for the main stick and the C stick. Is it possible to have a separate firmware that could include this?