Preheat the air fryer to 400°F.
Slice the russet potato into thin wedges and toss them with avocado oil, half of the sea salt, and half of the black pepper.
Place the potato wedges in the air fryer basket and cook for 18 minutes until they are golden and crisp.
While the potatoes cook, whisk together the brown rice flour, garlic powder, paprika, and the remaining sea salt and black pepper in a shallow bowl.
Gradually pour the light beer into the flour mixture, whisking until a smooth, bubbly batter forms.
Pat the cod fillets dry with a paper towel, then dip each piece into the batter to coat it thoroughly.
Arrange the battered fish in the air fryer basket and cook at 400°F for 10 minutes, turning once, until the coating is crisp and the fish flakes easily.
Serve the hot fish and chips immediately with a fresh lemon wedge.