Preheat your air fryer to 400°F to ensure it is hot enough to crisp the potatoes properly.
Slice the russet potato into thin, even wedges and toss them in a bowl with half of the avocado oil and a pinch of sea salt.
Place the potato wedges in the air fryer basket and cook for 15-20 minutes, shaking halfway through, until they are golden and tender.
While the chips cook, whisk together the flour, light beer, egg white, garlic powder, salt, and pepper in a shallow bowl until a smooth, bubbly batter forms.
Pat the cod fillets completely dry with a paper towel, then dip each piece into the beer batter to coat all sides thoroughly.
Lightly grease the air fryer rack with the remaining avocado oil, place the battered fish inside, and air fry at 375°F for 10-12 minutes until the crust is crunchy and the fish flakes easily.
Serve the hot fish and chips immediately with a fresh squeeze of lemon juice for a bright finish.