I've found that if you order any toppings that are potentially contaminated with wheat, they're good about letting you know.
This is my go-to place for gluten-free pizza. Theirs is the best in the area that I know of. Uno's gluten-free crust almost exactly matches the taste and the crispy, toasted texture of typical wheat-based New York pizza. Their sauce and toppings are excellent as well.
It does contain whey powder, so it may not be safe for some with a dairy allergy or sensitivity.
— Separate gluten-free menu