Let's see.
I do Keto and on my last trip I did the following restaurants: Space 220, Teppan Edo, California Grill, Steakhouse 71, Boma, Boathouse, Blaze Pizza, ice cream in HS and chocolate bar in MK. I usually had a keto type bar in the room for breakfast but I'm not a big breakfast eater any more. And I was not only low-carb but was in ketosis the entire trip
Boathouse is easy as they have a number of fish, meat and veggie options. I eat WELL there and it's always good.
Teppan Edo - just have then use veggies instead of rice.
CG - my dessert was the cheese plate, though I did taste my brother's items. Everything was Excellent!
Steakhouse 71 - Excellent food and service. The Wedge salad was very good. Did this location 2x during the trip. One tip - since I was a single the first time and a twofer the second time both times I was directed to an "alcove" in the back left. I didn't want to be there and was seated in a better location when I requested it.
Boma - Meat, salmon, tried some of the soups, salad. I even cheated and did a couple of the Zebra Domes

.
Space 220 - forget dinner, as no desserts are low carb so why pay for it?
Blaze Pizza has a Keto crust. Get the Build Your Own and go to town. Did this location several times on the trip.
In the Confectionery at the Magic Kingdom go to the little alcove all the way to the right. They have some dark chocolate no-sugar added bars there. They must have some low card sweetener because they tasted like milk chocolate to me.
Hollywood Scoops in HS has Fat-free, No Sugar Added Vanilla ice cream and Catalina Eddie's has a decent Caesar Salad with Chicken .
I'm sure there are more opportunities but these are the ones I used on that trip. On a past trip I also Did Earl OF Sandwich - if you do the Full Montegu and put all the filling on one side it's only about 30 carbs.
Between about 2 meal a day and all the walking I managed to keep myself in ketosis for the full trip and never has a blood sugar problem.
Hope this helps.