I just completed the opposite cruise, to Tierra del Fuego. There were a number of people in wheel chairs and scooters.
Everyone I talked to was very happy with the help and courtesy of the staff and ships company. We were on the Celebrity Eclipse.
The only down side was that when the ship didn’t doc at a wharf but anchored off shore, they would not tender “non walkers” to shore. That isn’t a problem on the Alaska cruise because I believe every stop is at a wharf.