Heat an air fryer to 375ºF. Meanwhile, wash 1 large russet potato and dry well. Peel if desired. Cut lengthwise into ¼-inch thick planks. Stack a few planks and cut lengthwise again into ¼-inch thick matchsticks, and repeat as needed. Transfer the fries to a large bowl. Add 1 teaspoon canola oil, ½ teaspoon kosher salt, ½ teaspoon garlic powder, season with black pepper, and toss to combine.
Lightly coat the air fryer basket with cooking spray. Place a single layer of fries in the basket (they can be touching but should not be stacked). Air fry for 7 minutes. Use tongs to flip the fries. Air fry until golden brown and crispy, about 7 minutes more. Remove from the basket. Repeat air frying any remaining fries as needed and serve immediately.