In a bowl, whisk together flour, baking powder, and salt. In another bowl, beat sugar and egg until fluffy, then mix in sour cream, melted butter, lemon juice, and lemon zest.
Fold dry ingredients into wet ingredients until just combined. Gently fold in blueberries, being careful not to crush them.
Grease four 4-oz ramekins and divide batter evenly among them, filling about two-thirds full.
Preheat air fryer to 320°F. Place ramekins in the basket and cook for 14-16 minutes until tops are golden and spring back when touched.
While cakes cool, whisk together powdered sugar, lemon juice, and lemon zest until smooth and pourable. Add more lemon juice if too thick.
Let cakes cool for 5 minutes, then drizzle generously with lemon glaze. Serve warm or at room temperature.