Slice the yellow onion into thick rings and cut the chicken breast into thin, even strips.
In a medium bowl, whisk together the flour, garlic powder, sea salt, and black pepper until well combined.
Slowly pour the light beer into the flour mixture, whisking constantly until a smooth, thick batter forms.
Dip the onion rings and chicken strips into the batter one by one, allowing any excess to drip back into the bowl.
Arrange the battered pieces in a single layer in an air fryer basket that has been lightly greased with avocado oil.
Air fry at 375°F for 12-15 minutes, flipping the pieces halfway through, until the coating is golden brown and the chicken is fully cooked.
While the rings and chicken are frying, whisk together the Greek yogurt, chipotle in adobo, and lime juice in a small bowl to create the aioli.
Serve the hot, crispy onion rings and chicken strips immediately with the smoky chipotle aioli on the side.