Slice the yellow onion into thick rings and cut the chicken breast into thin, even strips.
In a medium bowl, whisk together the chickpea flour, light beer, egg white, and half of the garlic powder, smoked paprika, sea salt, and black pepper until a smooth, bubbly batter forms.
Dip each onion ring and chicken strip into the batter, ensuring they are fully and evenly coated.
Arrange the coated onion rings and chicken in a single layer in an air fryer basket, working in batches if necessary to avoid overcrowding.
Lightly mist the tops with avocado oil spray and air fry at 375°F for 12-15 minutes, flipping halfway through, until the coating is golden brown and crunchy.
While the rings and chicken cook, whisk together the Greek yogurt, lemon juice, and the remaining spices in a small bowl to create the dipping sauce.
Serve the hot onion rings and chicken strips immediately alongside the chilled yogurt dip.