You don’t need to use the app store. You can just SSH into the device and run the usual apt commands from the command line. Yes, this is obviously nothing the general public would ever do, but we are on a news for nerds site here.
> buy up some mainstream phone and sell modded versions of it with kill switches
Making the connections for the several different kill switches (cellular, wifi, microphone) on a phone whose form factor was not expressly designed for that, would probably result in a rather ugly-looking hack. Moreover, on the PinePhone at least, the cell modem is separate from the wifi chip, so you can kill one while leaving the other on, but I believe that on most phones they are part of the same SoC.
> buy up some mainstream phone and sell modded versions of it with kill switches
Making the connections for the several different kill switches (cellular, wifi, microphone) on a phone whose form factor was not expressly designed for that, would probably result in a rather ugly-looking hack. Moreover, on the PinePhone at least, the cell modem is separate from the wifi chip, so you can kill one while leaving the other on, but I believe that on most phones they are part of the same SoC.