As to compiling on a smartphone:

RIGHT! This is the thing: it is intuitively obvious that one does not compile code on a smartphone. Why is this? Because a smartphone is not a computer.

It doesn't matter that we've now got devices as small or smaller than cell phones (such as the RPi) that are, in essence, just tiny desktop computers that run full-blown desktop operating systems. No, we've all been brainwashed that a smartphone can't do general-purpose computing, it's too tiny and too weak for that. Stick with the apps provided to you in the walled-garden ecosystem, and don't even try to do anything on your own without the supervision of your manufacturer or cell-service provider...