TL;DR it's possible to detect where you tapped on your phone screen somewhat reliably. Theoretically, someone could develop an app to associate screen location taps to keys and could pick out a password. Authors suggest phone manufacturers should limit access to accelerometers to prevent the attack.

This is extremely contrived and would take a shitload of skilled work to get right. It's way easier to make a phishing page coupled with social engineering to get what you want.