It's official! Much like the Picofly for the Switch, there is now a modchip for the original Xbox that uses the Raspberry Pi Pico. Only 4 resistors and 7 wires are required to solder the Pico to the LPC port. User "Shalx" designed it and has demonstrated on how it works in a video.
Download: https://github.com/shalxmva/modxo
Download: https://github.com/shalxmva/modxo