I have been thinking of a project where I would use a pi zero configured with the av outs on the board in a mobile media center. However, I do not want to have to carry a usb keyboard with me / buy a small one. Is there any library that I could use to render the gpio as a keyboard input? I would prefer to have this directly on boot, as I want to use a bootloader to be able to switch between retropie and OSMC. Do you guys know of anything out there that would fulfill these requirements?