Hello @sgryphon

from what I can tell there are two (three?) options to update SIM7020 firmware:

using UART2 (pins 22, 23) with a full firmware file using OTA with a delta firmware file

the procedure is described here and here.

There is something written about FOTA in the AT document as well. It sounds like one could download the delta firmware directly from the SIMCOM? server?

Sorry, I don't know the exact process to update firmware but I am curious myself so please keep us (me) updated about what you find.