If you can play the guitar i reckon you’d find it easy enough, something i keep meaning to learn. I’ve pottered about with the keyboard a bit, but never put in any serious effort like with the guitar… It’s easy enough to play with one hand, the problem comes with the coordination, the action on having to reverse your left hand completely messes the guitar coordination you have, i don’t think it’d take too long to learn the coordination though and once you do i think it’ll be shooty in, as your fingers will already have the suppleness and independent movement from the guitar playing. Well they should do, i don’t know how well you play the guitar, is it just strumming and chords you do or do you do more complex stuff with your left and right hands? i suppose that will make a difference..
As for reading music, it’s easy enough once you understand the basics it just needs the time put into it, and sheet music is designed for the piano, so a lot less stuff to consider for instance from reading music for the guitar, though the 2 clefs does puggle me as i’m used to just the one, no idea with they aren’t the same, ie. both middle notes are’t B, weird.