Preheat the air fryer to 350°F for 5 minutes. Combine the apple and frozen blueberries in an air fryer–safe baking pan or ramekin.
In a small bowl, combine the flour, sugar, cinnamon, and butter. Spoon the flour mixture over the fruit. Sprinkle a little extra flour over everything to cover any exposed fruit. Cook at 350°F for 15 minutes.