Reflashing forked devices to stock

I think someone made a prototype of this amiibo NFC+BLE functionality with real pixl.js but then went for own similar hardware and custom software and kept the name

I also haven't been able to connect to it yet with the normal Espruino IDE

makes no sense, as already explained - The firmware on those is completely different native code, not Espruino.

I've got no idea how the screen is connected but maybe SPI, and I assume they might have documented this HW version somewhere over in their project.

pinout is in https://github.com/solosky/pixl.js/tree/main/fw/application/src/boards

Guess I need to take it apart and see what exactly I've got.

you also need to take it apart to reflash it over SWD, unless you make softdevice+bootloader downgrade OTA package that may or may not work and if not you need to take it apart anyway