Toast bagel halves in air fryer at 370 degrees for 2 minutes.
Remove bagel halves from basket. Top each half of a bagel with a Tablespoon of marinara, three vegan pepperoni slices, and a heaping Tablespoon of non-dairy cheese.
Return bagel halves to the air fryer. Air fry at 370 degrees for 4 to 5 minutes. (Check at 4 minutes to see if the non-dairy cheese is melty enough for you. If not, continue one minute longer.)
Carefully remove bagel halves from basket. (I recommend spearing them with a fork to pull them out.) Top each bagel pizza with a pinch of chopped fresh basil (optional). The pizzas will be quite hot. So wait a couple of minutes before eating.
Bagels vary in size, and so adjust any toppings accordingly. If you're making several bagel pizzas, be aware that you'll likely have to cook in batches. With the bagels I used, a 3.7 quart air fryer could hold 2 bagel halves (one bagel), and a 5.8 quart air fryer could hold 3 bagel halves (1 1/2 bagels).