It would be nice if, for an additional fee, I could order an airport-safe charging cable for my phone. This is needed because chargers at the airport, on the plane, at the hotel, etc. are obvious places to implement spyware or rootkits, especially since the phone is often unlocked while plugged in, as the user is actively engaged with it. This means:
The cable permits charging but destroys all signalling in all distinct frequencies used by USB (of which there are a few). This might be as easy as disconnecting a data line, or as hard as adding some out-of-spec capacitance.
The cable is a weird color, so I’ll never make the mistake of inadvertently swapping it for a normal USB cable.
Gotta love an elegant hack. I vaguely remember doing something like this years ago.
The only issue with some phones is that it drops down to trickle charging (1/1.5 amps), because the data pins (IIRC) are also used to negotiate charging power. But that’s still a small price to pay.
Another solution would be to carry a couple battery banks with you (optionally using the data blockers as well). That way, you’re never exposing your phone to hacking or potential power issues, and the battery banks generally only have a very dumb microcontroller and may not even be flashable (at least not without opening up the unit and wiring in an ICSP).