Preheat oven to 190 Cº (375 Fº) or air fryer to 180 Cº (360 Fº).
In a mixing bowl whisk together oat flour, pinch salt, Greek yogurt, egg whites and olive oil. Stir (or blend) until you get a lump-free batter.
Heat a 20 cm (7.8 inches) nonstick skillet and spray with cooking spray (or grease the pan with oil or butter). Pour egg white pizza batter into hot pan and cover with a lid. Cook over low/ medium heat for a couple of minutes, then flip and cook on the other side for around 1 to 2 minutes more.
For the pizza sauce, in a small bowl mix together tomato sauce, salt, oregano, garlic powder and onion powder (if desired). Spread sauce over cooked egg white pizza crust. Top pizza with mozzarella and any additional toppings that you desire.
Drizzle with olive oil and bake in hot oven at 190 Cº (375 Fº) for 7 to 10 minutes or air fry at 180 Cº (360 Fº) for 5 to 8 minutes, until the cheese has melted.