Would it be feasible to use the enhanced nextion as programmer for an attached atmega, via the io interface, reading the hex file from the sdcard? Has anyone considered or tried something like this?
What do you think will happen to the program currently running on the arduino?
it should be overwritten.
If you write a boot loader similar to this one, it may be possible: GitHub - JAndrassy/ArduinoOTA: Arduino library to upload sketch over network to Arduino board with WiFi or Ethernet libraries