I develop hard- and software for AC-like systems and have a properly working (SODAQ SFF 4G-LTE) board with 256K separate additional non-volatile memory on the side. I am now finishing the sketch but need OTA after deployment of multiple units, which I find too complex.
I need someone who is able to implement a stable method including the server part to facilitate the over-the-air updates functionality; i.e. if the device receives a MQTT message telling it to update firmware it will: 1) Request the .bin firmware (Arduino IDE) from the remote server URL, 2) Download it and write it to the non-volatile memory (256K), set an install_firmware_update flag to true, reboot, update firmware, etc. etc.