It's close, and it's the first thing I found that made me think it would be possible someday. My first attempt would probably be to take one of those kits and a RbPi and figure out how to have it constantly record keystrokes. Or use a keylogger.
The use case for me is being able to carry a typewriter around and write on it without thinking about plugging it in to something, then taking a USB key off it later. Whereas that kit is more oriented to using with another computer.
It's also a project that I've accepted I'll tackle some year in the future as my list of fun projects is long and limited by a full time job and a side business. Thank you for the links!
It requires a desktop, Raspherry Pi or Android phone/tablet that supports USB OTG, http://www.corsair.com/en-us/landing/otg-compatibility-list
Maybe you could use a USB powered hub + hardware keylogger to record the keystrokes from the typewriter?