If you're using the oven, preheat to 350F and spray a small baking dish with nonstick cooking spray. For the air fryer, spray a barrel pan with nonstick cooking spray.
Mix the brown sugar, stevia or sugar substitute, ground cinnamon, and drained peaches in a bowl. Set aside.
Melt the butter for the topping before adding the remaining ingredients. Stir together until everything is evenly mixed.
Add the peach mixture to the baking or frying dish, followed by the topping. Air fry for 15-20 minutes or until the topping is crisp and there's very little juice remaining at the bottom (some is okay, as it will thicken at room temp). Bake for a similar time, though you may need a tiny bit longer.
Allow the peach crisp to cool for a few minutes before serving. Top with fat free whipped topping, low cal ice cream, or your choice of topping.