Preheat air fryer to 360°F for 2–3 minutes. Spray basket with olive or coconut oil spray.
Open biscuit can and separate dough. Use a 1-inch round cutter or bottle cap to punch a hole in the center of each biscuit. Save the holes.
Pour melted butter into a shallow bowl. Dip both sides of each raw donut in butter, letting excess drip off.
Place 3–4 butter-coated donuts in a single layer in the basket (not touching). Air fry at 360°F for 4–5 minutes, flip, then cook another 3–4 minutes until golden brown and puffed. Cook in batches.
Air fry donut holes at 360°F for 3–4 minutes, flipping once, until golden.
While donuts cook, mix granulated sugar and cinnamon in a shallow bowl.
As each donut comes out hot, immediately roll in cinnamon sugar. Roll a second time for a thicker coat. Place on a cooling rack. Repeat with all batches.
Serve immediately while warm.