Slice the yellow onion into thick rings and cut the chicken breast into thin, even strips.
In a medium bowl, whisk together the flour, light beer, egg white, and half of the garlic powder, paprika, salt, and pepper until a smooth, bubbly batter forms.
Pat the onion rings and chicken strips completely dry with a paper towel to ensure the batter adheres properly.
Dip each onion ring and chicken strip into the batter, allowing the excess to drip off, then place them in a single layer in the air fryer basket.
Lightly spray the pieces with avocado oil and air fry at 375°F for 12-15 minutes, flipping halfway through, until the coating is shatteringly crisp and golden.
While the rings and chicken cook, stir together the Greek yogurt, remaining spices, and chopped fresh chives in a small bowl to create the dipping sauce.
Serve the hot onion rings and chicken strips immediately with the chilled yogurt dip on the side.