Preheat your air fryer to 375°F (190°C) for about 5 minutes.
In a small bowl, mix the olive oil, garlic powder, onion powder, smoked paprika, salt, and pepper to create a marinade.
Pat the bratwursts dry with a paper towel. Coat them evenly with the marinade.
Place the seasoned bratwursts in a single layer in the air fryer basket, ensuring they do not touch for even cooking.
Cook the bratwursts in the air fryer for 12-15 minutes, flipping them halfway through cooking.
Use a meat thermometer to ensure they reach an internal temperature of 160°F (70°C).
If desired, toast the hamburger buns in the air fryer for the last 2-3 minutes of cooking time until golden brown.
Remove the bratwursts and let them rest for a couple of minutes.
Serve in buns with sautéed onions and bell peppers if desired.