The X1 runs linux on its Rockchip RV1126
It would be trivial for Bambu to add the modules for USB ethernet to the firmware, but then physically adding a USB hub in between the camera’s USB port (4 pin microfit) and the camera and USB ethernet adapter is non-trivial. There aren’t unused USB ports on the printer’s AP board.
See Open Source Software | Bambu Lab Wiki for a bit more info on the firmware.
I’ve tried a load of USB ethernet devices and other devices so can confirm the options required were not selected when they built the firmware.