Stir the breadcrumbs and milk together in a large bowl. Let sit 5 minutes until the milk is fully absorbed.

Add the ground beef, Parmesan, egg, garlic, grated onion, Italian seasoning, salt, and pepper. Mix by hand just until combined — do not overwork.

Portion with a 1.5-tablespoon scoop and roll into 16 meatballs.

Preheat the air fryer to 375°F. Arrange the meatballs in a single layer with space between them, working in batches if needed. Air fry 10 to 12 minutes, turning once, until they reach an internal temperature of 165°F.

Heat the olive oil in a saucepan over medium heat. Add the garlic and cook 30 seconds until fragrant, without browning.

Stir in the crushed tomatoes, tomato paste, sugar, oregano, basil, salt, and pepper. Bring to a bare simmer.

Reduce heat and simmer uncovered 20 minutes, stirring occasionally, until thick enough to coat a spoon.

Add the cooked meatballs to the sauce and let them sit at least 5 minutes.

Split each roll lengthwise without cutting through. Lay the mozzarella directly on the open bread. Air fry at 350°F for 2 to 3 minutes until melted and bubbling.

Spoon 4 sauced meatballs into each roll. Top with additional sauce and the Parmesan.

Return to the air fryer at 350°F for 2 minutes to heat through. Serve immediately.