Nokia N9, it was my first smartphone, it ran Linux, as in you could run sudo apt install in it and yes, sudo worked and you could get root access from factory. It was very sturdy, keyboard did some vibrations when you pressed so you got some tactile feedback which was invaluable in convincing me to use a phone with no buttons, it had gesture navigation which took years to arrive in other phones, plus some games I never got to finish and now I can't play anymore.