How 'bout a Linux phone :
Ubuntu PhoneIMHO no use with iOS, Android or Mobile Windows in terms of secure privacy - as they all have numerous backdoors deeply nested in their core OS.
I repeat: After these privacy issues on the desktop OS, you are still thinking about Ubuntu Phone?
Go to privacy settings and turn off "Include online search results" solves the whole privacy issue. Source is completely open so you can look for any backdoors.

I still prefer this over any os where you can be 100% sure your data is send to national security agencies and used for marketing purposes