That's one of my favorite things about Dnd. "The World" is the DM's interpretation of a world or their own world. Even if they were running an otherwise stock Forgotten Realms setting they can add as much steampunk or magipunk elements as they please, including superpowered wheelchairs for adventurers. In your world there would probably be something different than wheelchairs if there's anything because it really just comes down to preference.