Combine the stewed tomatoes and tomato paste in a food processor. Add the garlic, onion, Italian seasoning, salt, and oregano. Process until you have a thick, dense sauce, about double the thickness of pasta sauce.

Cut the French loaf in half lengthwise, then cut each half in half again to create four boat-like halves.

Spread the prepared pizza sauce generously over each half of the French bread.

Sprinkle the shredded mozzarella cheese evenly over the sauce, then arrange the pepperoni slices on top.

Place the assembled French bread pizzas into the air fryer basket. Cook at 350°F (175°C) for 6 minutes, or until the crust is crispy and the cheese is melted and bubbly. Alternatively, bake in a preheated oven at 450°F (230°C) for 12-15 minutes, then broil for 1-2 minutes to lightly brown the cheese.

Serve immediately. Optional: top with grated Parmesan cheese or crushed red pepper flakes.