I need to estimate a complexity of words for typists.
For example “suffer” is easy than “people” becouse “o” and “p” is harder than “e” and “r”.
Any key pressed by little finger is more hard to hit than by index finger.
And move finger from basic position is more harder than do not move.
And use shift key also add hardness.
What approach can be imlemented in this case?
I would check out the Carpalx website. The site details how they rate different keyboard layouts for typists, and already has some open-source software that implements their algorithms for any given keyboard layout. (Make sure to check out the typing effort, model parameters and keyboard evaluation sections.)