Add chicken parts to a gallon size resealable plastic baggie or large bowl. Add the hot sauce*, if using. Then pour the buttermilk over the chicken.
Seal the baggie and gently massage it to mix (If using a bowl, stir, then cover with plastic wrap). Lay the baggie on its side on a small sheet pan. Place baggie or bowl in the fridge for minimum 1 hour, up to 24 hours or so for best results.
Remove the chicken from the fridge. In a shallow dish whisk together flour, corn starch, salt, pepper, paprika, garlic powder, onion powder.
Preheat the air fryer to 390°F for about 3 minutes.
Line the air fryer basket with parchment paper that is perforated (with holes in it). Or just use a fine mesh basket.
Using tongs or your hand, take out a piece of the chicken and gently dredge it in the flour mixture. Carefully shake off any excess. Set the piece in the air fryer basket on the parchment paper. Fill the basket with a single layer of chicken, with no pieces overlapping.
Set the air fryer to 390°F for 30 minutes. After 15 minutes, open and spritz the chicken with oil if you see any dry flour spots. Then flip all of the pieces over and continue cooking the remaining 10-15 minutes.
Check the temperature with an instant read thermometer. White meat should read 165°F, and dark meat 175-180°F.
You can cook the chicken in batches. Just cook the first batch and set it aside when done, just like you would when making traditional fried chicken.When all of the chicken is air fried, just add the cooled pieces to the air fryer at a low temperature, about 225°F, and heat it for a few minutes, until you are happy with how hot it is. Then serve.