Hi,
I’m creating a similar hardware project except I’m communicating to Azure.
For the BG96, I’m using the https://www.quectel.com/product/bg96minipcIe.htm board.
This has the SIM interface built on.
I just communicate to the BG96 via a uart on a STM32 and use a couple of extra I/O lines for resetting the BG96, looking at the online pin etc.
This is all currently working and sending data to Azure via MQTT.
The USB interface is purely for testing and uploading of security tokens etc during manufacture.
The SIM card socket is on the underside of the BG96 module, so no additional design & interfacing in this area is required.
Neil.