A host processor is required to perform the fragmentation re-assembly.
It can also be used to flash the xDot over serial with the default bootloader.
This open-hardware board uses xDot with an external flash.
It is used with mbed-os for lorawan FUOTA demos, the lorawan fuota example includes a bootloader to flash the xDot from flash, it does not have the serial transfer of firmware of MTS bootloader. The example is using the mbed-os lorawan stack with the full FUOTA application with multicast setup and packet fragmentation implemented in an xDot firmware with no AT commands.
https://github.com/L-Tek/L-Tek-FF1705