Well not completely black, for example Quectel modem on PinePhone is running it's own Linux system, which has many parts open sourced, and is at least pokeable

Well not completely black, for example Quectel modem on PinePhone is running it's own Linux system, which has many parts open sourced, and is at least pokeable and allows for not so hard reverse engineering. For anyone with enough time, now that Ghidra is available, it should be fairly straightforward to see what's hiding in there, even in the proprietary parts. You should be able to even run shell commands via some AT commands, if not via adb. https://osmocom.org/projects/quectel-modems/wiki/Quectel https://osmocom.org/projects/quectel-modems/wiki/Quectel