Being a diabetic who frequents WDW on the
DDP, i can tell you the answer to the appetizer question is no..
Ways we work around the dessert issue:
Many locations already have an NSA or 'sugar-free' dessert option. I have found at various times cakes, pies, cookies, and mousses that were NSA. All buffets and most (not all, but most of the popular ones for sure) non-buffet locations are offering one of these options.
Other locations without an obvious option can get NSA ice cream or a fruit plate to substitute. I once got a lovely dish of berries with two scoops of NSA ice cream while my travelmate had to suffer through a dry, almost bitter chocolate cake.... too bad for him
..and then there's
my preferred option (not being fond of dessert in general and artificially sweetened desserts in particular):
I order a regular dessert to go, and my travelmate eats it later - and I claim one of 'his' snack credits for fruit or a pretzel or ... any old thing that i want.
I will say that after hiking around a park all day, I sometimes just eat low-carb for dinner and go ahead and have the 'regular' dessert, but then I am a type-I and have more trouble with low blood glucose than with high.