Cut the bell peppers into strips and slice the onion. Toss them in a bowl with the olive oil, garlic powder, salt, and pepper.
Spread the seasoned peppers and onions in the air fryer basket and lay the sausage links on top in a single layer.
Cook at 380°F for 15 to 20 minutes, shaking the basket and turning the sausages every 5 minutes, until the sausage is browned and cooked through (160°F for pork, 165°F for chicken or turkey) and the vegetables are soft and caramelized.
Serve as is, or pile into toasted hoagie rolls.
Notes
Meal prep like I did: cook a big batch (I did 8 links and a full tray of veggies), refrigerate 4–5 days, and reheat at 350°F for a few minutes.
Don't overcrowd the basket — cook in a single layer (or in batches) so the vegetables roast instead of steam.
Pork sausage is done at 160°F internal temp (165°F for chicken or turkey).
Starting from frozen sausage? Add 5–7 minutes and always verify 160°F inside.