Preheat your air fryer to 400°F (200°C).
Slice the Russet potato into thin wedges and pat them completely dry with a paper towel.
In a small bowl, toss the potato wedges with half of the avocado oil, half of the sea salt, and half of the black pepper.
Place the potato wedges in the air fryer basket in a single layer and cook for 15-20 minutes, shaking halfway through, until golden and crisp.
While the potatoes cook, whisk together the flour, light beer, garlic powder, paprika, and the remaining salt and pepper in a shallow dish until a smooth batter forms.
Pat the cod fillets dry and dip each piece into the batter, ensuring it is fully coated.
Once the potatoes are done, remove them and keep warm. Lightly grease the air fryer basket with the remaining avocado oil.
Place the battered fish in the basket and air fry at 400°F for 8-10 minutes, flipping gently halfway through, until the coating is crispy and the fish reaches an internal temperature of 145°F.
Serve the crispy fish and chips immediately with a fresh lemon wedge.