It appears that on an ESP32, the last 3 bytes of the MAC go into the device id ("esp32_4D3E1C").
What determines what the device id looks like, and is that template easily changable?
I need something different and don't want to have to touch the conf9.json for each device, and want the new device id to be used when doing an mos aws-iot-setup.
Ignore the above (I'd delete the post if I could). Solution for my real problem here.