Hi verdinfloy,
Honestly, I can't recommend any courses but "accessibility in videogames, apps or any digital media" sounds like a dissertation project to me, mainly because it sounds niche. You might find that no university offers a degree specifically in that area but you could always do your masters dissertation on that topic if you can find a willing supervisor. There is no guarantee that your masters supervisor will let you or be able to help you. Though you could possibly apply to an MRes degree where you solely research that specific topic.
I hope that is helpful.