Preheat the air fryer to 400°F (204°C).
Place the chicken drumettes in a single layer in the air fryer basket (use air-fryer parchment if desired) and cook for 8 minutes.
Flip the drumettes and continue cooking for another 8 minutes, then check for crispness and doneness; if needed, cook an additional 2 minutes.
While the wings cook, combine the Dijon mustard, honey, unsalted butter, garlic powder, cayenne pepper, and kosher salt in a 12-inch skillet over medium heat and warm until the butter melts and the sauce is smooth, about 1–2 minutes.
Remove the skillet from the heat.
Add the cooked drumettes to the warm honey mustard sauce and toss until evenly coated.
Optionally sprinkle with crushed red pepper flakes for extra heat and serve immediately.