Cook chorizo in a large skillet over medium-high heat, stirring frequently, until it turns dark red, 6 to 8 minutes. Remove from the skillet.

Melt bacon grease in the same skillet over medium-high heat. Add diced potatoes and cook, stirring occasionally, 8 to 10 minutes. Add onion and serrano pepper; cook and stir until potatoes are fork-tender, onion is translucent, and serrano pepper is soft, 2 to 6 minutes. Add eggs and chorizo; stir until cooked and completely incorporated into potato mixture, about 5 minutes. Season with salt and pepper.

Meanwhile, heat tortillas in a large skillet or directly over the grates of a gas stove until soft and pliable. Place 1/3 cup chorizo mixture down the center of a tortilla. Fold top and bottom of tortilla over the filling, then roll into a burrito shape. Mist with cooking spray and place into the air fryer basket. Repeat to make remaining burritos.