In a large bowl, whisk together 1 cup yellow cornmeal, 1 cup all-purpose flour, 1 3/4 teaspoons baking powder, 2 tablespoons sugar, 3/4 teaspoon salt, and 1 1/4 teaspoons garlic powder until evenly combined.
In a separate bowl, beat 1 large egg. Add 6 tablespoons low-fat buttermilk and 3 tablespoons unsalted butter (melted) and stir until blended.
Stir 3 tablespoons grated yellow onion and 2 tablespoons chopped green onion into the wet mixture.
Pour the wet mixture into the dry ingredients and gently stir until just combined; do not overmix. Let the batter rest for 5 minutes.
While the batter rests, preheat the air fryer to 400°F for 5 minutes.
Lightly spray the air-fryer basket with nonstick cooking spray. Using a tablespoon, scoop level tablespoonfuls of batter and drop them into the basket, spacing them so they do not touch. Work in batches if necessary to avoid overcrowding.
Set the air fryer to 380°F and cook the hush puppies for 4–5 minutes.
Carefully flip each hush puppy (use tongs or a small spatula) and cook for an additional 3–5 minutes, or until they are golden brown and crispy.
Remove the hush puppies from the air fryer and serve warm.