Slavko,
Are you asking if you can use the Galileo to drive a USB port as if it were a keyboard or if you can use a keyboard on a Galileo. The answers so far appear to target the latter, but I think you asked about the former. Can you clarify?
In your second question, you asked about drivers. Do you really want to write a UEFI driver? Clearly, you can, but is that what you really want? If you want a new driver for the Linux kernel built by Yocto, it's highly unlikely you need a UEFI driver. Can you clarify?
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dnl