In a medium saucepan, combine the ketchup, whiskey, vinegar, soy sauce, onion, garlic, chili powder, and paprika over medium heat. Cook at a steady simmer, stirring occasionally, until the vegetables soften and the sauce thickens slightly, about 15 minutes. Taste and add salt and pepper if necessary. (Use right away or cool, cover and refrigerate for up to a week.)
Rinse and drain the jackfruit in a colander, pressing down to extract as much water as possible. Run your hands through the pieces, pulling and separating them into shreds with your fingers.
Place the olive oil in a large skillet over medium-high heat. When it’s hot, add the jackfruit and cook, stirring occasionally, until browned and crisp in places, 2 to 3 minutes. Add the sauce and bring to a boil, then adjust the heat so the mixture bubbles gently. Cook, stirring once in a while, until the sauce has thickened and the jackfruit has absorbed some of the flavor, 15 to 20 minutes.