In a large bowl, combine the flaked salmon, panko, egg, 2 tablespoons mayonnaise, Dijon, green onions, lemon juice, garlic powder, salt, and pepper. Mix until evenly combined.
Shape the mixture into 8 patties, about 2 1/2 inches wide and 1/2 inch thick. Place on a plate and refrigerate for 10 minutes to firm up.
Preheat the air fryer to 400°F (200°C) for 3 minutes. Lightly spray the air fryer basket with cooking spray.
Arrange half the salmon cakes in the basket in a single layer, leaving space between them. Spray the tops lightly with cooking spray.
Air fry for 8–10 minutes, flipping halfway through, until golden brown and crispy. Repeat with the remaining cakes.
While the cakes cook, make the aioli: in a small bowl, whisk together 1/4 cup mayonnaise, 1 tablespoon lemon juice, chopped dill, minced garlic, and lemon zest. Season with a pinch of salt.
Serve the salmon cakes warm with the lemon dill aioli on the side.