Pat the shrimp dry with paper towels to remove excess moisture for maximum crispiness.
In a shallow bowl, mix cornstarch with garlic powder, salt, and pepper. Toss shrimp in the mixture until lightly coated.
In a separate bowl, whisk together mayonnaise, honey, sweetened condensed milk, and lemon juice to make the honey sauce.
Preheat your air fryer to 375°F (190°C) for 3 minutes. Lightly spray the basket with oil.
Arrange shrimp in a single layer in the air fryer basket, ensuring they don't touch. Cook for 10-12 minutes, shaking halfway, until golden and crispy.
While shrimp cook, toast walnut halves in a dry skillet over medium heat for 3-4 minutes until fragrant and lightly browned.
Remove shrimp from air fryer and immediately toss with the honey sauce and toasted walnuts until fully coated.
Serve hot over steamed rice or noodles, garnished with green onions if desired.