It is only irrelevant because devices made in this century put a lot of work into not transmitting outside of the intended frequencies.

My old Nokia would smash the whole range of AM/FM and UHF bands.

I don't know about higher frequencies that could escape one of these cages intended to block WiFi/5G/GPS but it is possible in theory and then it would be likely a backdoor that only becomes active when no signal can be detected.