If Disney does not restrict shore excursions to their tours only, unknown at this time as there is chatter that may happen with many different cruise lines when cruising begins, you may want to check out Chilkoot Charters in Skagway. If I was to do another tour of this type in Skagway, I’d book them again without hesitation.
Locally owned Skagway company, we used them for their Yukon Train/bus tour and loved the experience. Their busses are the smaller 15-20 Passenger hotel shuttle-type busses, Smaller group size plus made it very easy to make more stops along the way as well as time stops to when the larger cruise ship tour busses were not at the main points such as the Alaska sign. We were also able to U-turn & stop for 15-20 min along the side of the road twice, once to watch a baby brown bear and once at an overlook to get some great pics of the White Pass RR passing by in the canyon below, as the larger busses passed on by.
https://chilkootcharters.com/