In a wheelchair yes in a scooter not if it is a tendered port, even the wheelchair they will need to step onto the ship and sit and the wheelchair will be loaded separately.
DO NOT let them pick up the wheelchair with your friend in it and carry it. That is completely unsafe no wheelchair is designed to be lifted with someone in it and many have pieces the let go or come apart, for instance arms that swing out of the way. The crew wants to be helpful but are completely ignorant of how to handle disabled passengers or their equipment for that matter.
Some times you must be very insistant as many don't speak English.
If you are docked you can get off with the scooter in most cases though it is best on the gangplank to have someone walk the scooter off and your friend walk off then get on the scooter, assuming they can walk that much.
The Opposite of Love is not Hate, But Indifference