The Fairphone (Gen. 6)

If they'd just provide a physical switch (not software-based but actually cutting off the respective chips and antennae from electricity) to go full offline (no GPS, no Wifi, no mobile connection, ...) they'd effortlessly at least double their market potential.

I'd be happiest if they'd provide a physical switch for the microphone and cameras. That way, you could have a private conversation and be sure you're not being recorded.

Turning off connectivity doesn't help as much to guarantee your privacy as the phone could theoretically be recording and then upload the recording later, when you turn it back on (if it was thoroughly compromised, which admittedly seems unlikely, but nevertheless it would be nice to have some guarantee that it's impossible).

The easiest solution to such strict privacy needs is to not carry the phones. But then again you also need to worry about other means of espionage.

I don't think it's easy to not carry a phone, nowadays. Let's say I'm meeting up with someone: I'll need to use navigation, potentially message them if I'm running late, and so on.

Then once I'm there, what do I do with the phone? Ask to put it in a separate room and hope that the microphone isn't powerful enough to pick up our conversation?

I could turn it off entirely, but what if someone needs to call me for an emergency?

For me, as a user, the easiest solution would be to have a killswitch. I understand that building it would be more work, of course :)