@pavel Is this is a theoretical consideration or are you trying to solve a practical problem of powering a computing device in a specific situation?
@pavel One could then calculate a power estimate from typing behaviour and physical properties of the relevant typewriter component.
@pavel While drawing energy from fingers would be surely feasible, other body parts might be able to provide same power with more user comfort, because the required power will be only a small fraction of what they are capable of. This is illustrated by the fact that I managed to melt steel with power of legs of a friend who was helping me by pedalling, directly from the generator, without intermediate storage in batteries.
@pavel I could develop a small generator based on a stepper motor and a piece of string with 2 handles on the ends wound on its axle, operated by both arms that could give quite some power. I tried this and a stepper motor gives good power even with a crank directly attached to the axle without any gears.