Same food/drink options at most theaters:
Candy
Popcorn
Pretzels
Chips
Bottled water
Liquor
Frozè
Soda
The food app is just for convenience to order from your seat. The same food/drink options.
Things in the ‘sweet shop’ are just glorified snacks that are arranged to be Potter-themed so they can justify charging you twice as much for the same things you would get at any other show.
"Mostly, I loved the size of these people's emotions. Nobody has emotions this size anymore. Outsized emotions. Operatic emotions. Kushemski and Vanda are like Tristan and Isolde, they're Paolo and Francesca. Nobody's in total thrall like this anymore. Nobody's overcome by passion like this, or goes through this kind of rage." Thomas, Venus in Fur