My Kercpa (size tiny squirrel folk) wizard Rakiki has an owlcat (size small) familiar that he rides. The idea for the owlcat I found on DM's Guild where they had a size tiny, medium and large variant, so I created a small variant to use as a mount for a tiny character. Will try and make a variant with a kercpa flying on its back as well (and a variant with the owlcat flying), time permitting of course.