Vim comes from a time when we did not have screens, you had to print out the code on paper. Probably why it works surprisingly well on mobile. Being able to see the code is a luxury. Typing speed is also not an issue when writing a program, although modern languages are verbose compared to assembly.
I would worry about ergonomics when working on mobile though, like neck/back and thumb issues.
I would suggest having the terminal screen built into glasses, and a wireless keyboard for input. Maybe we can innovate on the keyboard part so it can fit in your pocket
It works quite well. There is a lack of precision trying to drag the cursor around on Android, which is made worse on the <$100 quality devices. Using vim's keyboard commands, I can precisely edit text far easier than anything else I have used on a phone. I never used emacs because I'm not a fan of chords, and this is amplified on the phone. However, people who swipe text may like emacs chords over vim's commands and modes.