The berry Napoleon

No

That would depend on the cake you order or select. The bakery has lot of choices. For off the counter orders, you can ask for the ingredients. For a custom order, you should be able request for a cake without gelatin.

They do but recently failed the CDC Guidelines...last seating is 10:30pm I came at 10:26pm, there were no seats left so we did not get to sit but they are open for take out and delivery til 12am

Ask for sugar free or low sugar pastry, I don't know if they make sugar free cakes. What your dad has to do is keep a good diet, exercises, lots of water, and take his medications, so he can enjoy a very little slice of a regular cake for a special event, once in a while, if you can not find a special cake. Besides diet, a diabetic patien gotta be carefully how much eats.