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).