Combine ketchup, molasses, brown sugar, white vinegar, Worcestershire sauce, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1/2 teaspoon salt, 1/2 teaspoon smoked paprika, 1/2 teaspoon chili powder, and 1/4 teaspoon black pepper in a small saucepan.
Add the chopped peaches to the saucepan, bring the mixture to a boil, then reduce heat and simmer for about 15 minutes until the peaches are tender.
Carefully transfer the peach barbecue sauce to a blender (do not seal fully) and pulse to your desired consistency, then return the sauce to a bowl and taste; adjust seasoning, heat, or sweetness as desired.
While the sauce simmers, make the breading: in a bowl combine cornmeal, panko, 1 teaspoon salt, 1 teaspoon chili powder, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1/2 teaspoon smoked paprika, 1/2 teaspoon oregano, 1/2 teaspoon black pepper, and the optional 1/4–1/2 teaspoon cayenne if using.
In a separate bowl whisk together the beaten egg and 2 tablespoons milk.
Place the 1/3 cup flour in a shallow dish or bag. Add the chicken tenders and toss to coat in flour, then remove and tap off excess.
Dip each floured tender into the egg mixture, letting excess drip off, then place in the bag or bowl with the cornmeal–panko mixture and press the breading onto the chicken until well coated.
Heat enough vegetable oil to lightly coat the bottom of a large nonstick skillet over medium-high heat until hot but not smoking.
Cook the tenders in batches, 3–4 minutes per side, until golden brown and an instant-read thermometer inserted into the thickest part registers 165°F (74°C). Do not overcrowd the pan.
Transfer cooked tenders to a rack or paper towel-lined plate while you finish the remaining batches.
Dip each hot chicken tender into the peach barbecue sauce and serve immediately.