Ahoy Stephany!
Welcome to planDisney! So glad you charted a course to our site to ask your question. That’s what we are here for!
You’ve already gone to the right place to check if a collapsible wagon is allowed on Disney Cruise Line.
This link takes you to what I call the “no no” list. While wagons are not allowed, it does specifically say that a collapsible wagon would be fine. But here’s the thing: there are many areas on the ship where it would be far easier maneuvering if the kids were simply walking. Not to discourage you from bringing your wagon, but just wanting you to go in knowing that you may not actually use it all that much.
Perhaps your goal is to use a collapsible wagon while ashore or on
Castaway Cay. If so, my preference would be to use one or the strollers or wagons available from Disney Cruise Line. These are offered on a first come, first served basis, but I find that the less stuff I have to haul onboard, the better!
Wishing you a very MAGICal cruise and lots of memory making with your family!
SEA ya real soon!
Sherry