Preheat your air fryer to 400°F to ensure it is hot enough to crisp the potatoes.
Slice the russet potato into 1/2-inch thick wedges, pat them dry, and toss with avocado oil and a pinch of sea salt.
Place the potato wedges in the air fryer basket and cook for 18-20 minutes, shaking the basket halfway through until they are golden and tender.
While the chips cook, whisk together the flour, baking powder, sea salt, black pepper, and smoked paprika in a shallow bowl.
Slowly pour the cold light beer into the flour mixture, whisking until a smooth, thick batter forms that coats the back of a spoon.
Pat the cod fillets very dry with paper towels, then dip each piece into the beer batter, allowing any excess to drip off.
Lightly grease the air fryer rack, place the battered fish inside, and cook at 375°F for 10-12 minutes, flipping carefully halfway through, until the coating is shattered-crisp.
Serve the hot fish and chips immediately with a fresh squeeze of lemon juice.