Prep topping: Pulse pecans with brown sugar in a food processor until finely chopped/combined. Stir in maple syrup to make a sticky praline mix.
First cook: Arrange bacon halves in a single layer in the air fryer. Air fry at 350°F (175°C) for 5 minutes.
Top: Press or brush the pecan-sugar-maple mix onto the bacon.
Finish: Air fry an additional 12 minutes at 350°F (175°C) until caramelized and crisp (watch for sugar scorching). Cool a few minutes so the coating sets.