Combine ground beef, ground pork, panko, shallot, eggs, salt and pepper in a large bowl. Roll into 48 (1-inch) balls and place on a large rimmed baking sheet.
Heat 1 tablespoon oil in a large nonstick skillet over medium-high heat. Add half of the meatballs; cook, turning often, until evenly browned on all sides, about 5 minutes. Transfer the meatballs to a 5- or 6-quart slow cooker. Repeat with the remaining 1 tablespoon oil and the remaining meatballs. Set the skillet aside (do not wipe clean).
Whisk barbecue sauce, grape jelly, ketchup and hot sauce together in a small bowl or glass measuring cup. Add the sauce mixture to the hot skillet and stir to scrape up any browned bits from the bottom of the skillet. Pour the sauce over the meatballs in the slow cooker; gently stir to combine. Cover and cook on Low until the sauce thickens and coats the meatballs and a thermometer inserted into the meatballs registers 160°F, 3 to 4 hours. Garnish with chives, if desired.
