Slice the yellow onion into 1/2-inch thick rings and separate them carefully, discarding the very small inner pieces.
In a medium bowl, whisk together the all-purpose flour, unflavored whey protein isolate, garlic powder, and smoked paprika.
In a separate small bowl, lightly whisk the egg white and light beer until the mixture is combined and slightly frothy.
Pour the wet ingredients into the dry mixture and whisk until a smooth, thick batter forms that can coat the back of a spoon.
Dip each onion ring into the beer batter until fully submerged, allowing any excess batter to drip off before placing them in the air fryer.
Arrange the battered rings in a single layer in the air fryer basket, ensuring they do not overlap, and lightly spray with olive oil.
Air fry at 375°F (190°C) for 8-10 minutes, flipping halfway through, until the coating is golden brown and crispy.
While the onions cook, stir together the non-fat Greek yogurt, lemon juice, hot sauce, sea salt, and black pepper in a small bowl to create the zesty dip.
Serve the hot onion rings immediately alongside the chilled yogurt dip for a high-protein, clean-eating snack or side dish.