Offtopic:

>Even if that device doesn't have the ability to turn on Airplane Mode or to turn off the transmitters through the Control Center of iOS.

IIRC, the default on iOS is that anyone with your locked device can enable airplane mode which is concerning simply for thieves. But I suppose they have to use faraday bags anyway because of the Find My network.

You can (and should) disable access to the Control Center when the phone is locked. You could, alternately, remove the “airplane mode” button from the control center.