There exist cellular and wireless cards for PCs too, and still a Linux PC is on our side. But if that's somehow not enough: You could use proof-carrying code o

There exist cellular and wireless cards for PCs too, and still a Linux PC is on our side. But if that's somehow not enough: You could use proof-carrying code or reproducible artifacts to keep the radio stack out of the users' control while still making it obvious what it is that radio stack does. The BIOS analog would then only accept radio code that behaves in a particular way, but it would be clear from the (open) source that the radio code is not spying on you.