Heat oven to 425°F; oil a rimmed sheet. Soak panko in milk 3 minutes; gently mix with pork, bacon, egg, salt, pepper, and sage. Shape 24 equal meatballs.
Bake 18 to 22 minutes until centers reach 160°F. Lift from rendered fat with a slotted spatula.
Meanwhile, pour bourbon into a saucepan away from flame. Gently simmer 4 to 5 minutes. Stir in ketchup, broth, molasses, vinegar, and Dijon; return to simmer.
Transfer hot sauce and meatballs to a 4-quart slow cooker. Cover; cook on HIGH 2 hours, gently turning once, until centers reach 165°F. Uncover final 10 to 15 minutes if glaze needs reducing.
Gently coat; serve about 3 meatballs per appetizer portion. Keep covered on WARM only while food stays at least 140°F.