Grate the zucchini and use a clean towel or paper towel to squeeze out moisture. Finely chop or grate the onion.
In a large bowl, mix ground turkey, zucchini, onion, egg, oats, herbs, Dijon mustard, garlic powder, salt, and pepper. Stir just until combined.
Form into 1½-inch meatballs (about 16–18) using clean hands or a cookie scoop.
Preheat air fryer to 375°F (190°C) for 3–5 minutes.
Lightly spray the air fryer basket. Arrange meatballs in a single layer. Air fry for 10–12 minutes, shaking the basket halfway, until golden brown and cooked through (internal temp 165°F/74°C).
Serve warm with your favorite sauce or sides, or store for meal prep.