Ndravuni / Dravuni Island is not really a very bad place for handicapped people, because as long as you are able to get into and out of the tenderboats you will be able to go in your wheelchair from the pier to the beach and around the small local village next to the pier !
By wheelchair you could also go to the cemetery, that path is quite flat and also quite wide, but all other sights will be much too hard for you !
On Dravuni / Ndravuni Island you can only walk, there are no taxis, no rental cars, not even carriages etc. There are 2 main paths across the island: one from the pier to the other side of the island and another path going from the viewpoint to the cemetery of the island.
There are some hills on that island, so you need to climb a bit here or there, but the paths are mostly easy for everybody who is not handicapped !
I came by the cruiseship "Dawn Princess" to Dravuni island and the only way to go ashore was by tenderboat, that means you had to queue up for some time in order to find a seat on a tender taking you ashore.
The island is quite small and easy walkable on your own, so there were no tours organized by the ship-company, but only a small map of the island printed out by the touroffice, showing the most important sights and beaches.
They had quite a good and stable pier on the island !