Interestingly, my iPhone X when booted to diags with usbserial enabled shows up as an iPhone 3G booted to DFU mode in Apple Configurator.
In PurpleSNIFF, it shows up as a "Diags CDC Serial" and the hardware model S5L8900X.
Purplerestore3 detects it as some S5L8900x device.
#appleinternal