[Question] Cross-Flashing Generic Firmware Between Hardware Vendors

[moriel5]

Note, this is not about flashing from one provider (i.e. Dell, Lenovo, etc.) to another, but rather between the manufacturers (i.e. Sierra, Quectel):

While reading through quite some information (led by a rabbit hole originating in ThinkPad L15 Gen1/Gen2 cellular modem whitelisting), I had the idea, that if we could flash the original manufacturer's (Qualcomm, Intel/Mediatek/Apple, etc.) generic firmware on a card (from Quectel, Sierra, Fibocomm, etc.) we might be able to unlock phone calls on the desktop (provided that a suitable software stack exists), and not just texting and data.

My question, would something like this even be possible? After all, there could be hardware differences regarding voltages and such between the manufacturers (say, Sierra to Quectel or generic Qualcomm, or Fibocomm to generic Intel), and that would very well put a stop to this (unless someone manages to build custom firmwares, which due to the source code situation there, is pretty much a pipe dream at this point).