Imo, the only solution is every device with an antenna must be legally required to put a manual off switch.
Cell service, wifi, Bluetooth, any future service. If it broadcasts it needs a physical off switch.
If I sold my car to a government official and they found out I had hidden a camera, microphone and GPS in the car, I’d get a visit from the FBI. Yet companies do it with impunity. Does the CEO of Subaru have recordings of Bernie Sanders driving in his car?