My kids have milk allergies (not life threatening) would it make sense to make a birthday party here. Would they have something to eat other than pizza?

I guess but don't expect a big selection.

Yes they have french fries and other options on the party menu

I believe you can work with the staff to customize your menu. Last time I was there for a party they had Bagels for the adults

As Ilana answered, there is only pizza.

Nope. Only pizza.