Remove the silver membrane from the back of the ribs by sliding a butter knife under it and pulling it off with a paper towel; pat the ribs dry. This helps the meat become extra tender during the slow cook.

Mix garlic powder, onion powder, smoked paprika, black pepper, salt, and cayenne pepper in a small bowl. Rub the spice mixture all over both sides of the ribs, pressing lightly to coat.

Whisk together BBQ sauce, crushed pineapple with its juice, brown sugar, soy sauce, apple cider vinegar, minced garlic cloves, and Worcestershire sauce until smooth. Keep whisking until the brown sugar dissolves and the sauce looks evenly blended.

Pour about 1/3 of the pineapple BBQ sauce into the bottom of the slow cooker. Place the ribs inside, standing them upright along the edges if needed (cut the rack in half for a better fit).

Pour the remaining sauce over and around the ribs, making sure they're well coated. Spoon any sauce from the edges back onto the top so the surface stays sauced.

Cover and cook on LOW for 7–8 hours until the meat is fall-off-the-bone tender and pulls away easily. Visual cue: the ribs should look very soft, with sauce bubbling around the edges.

Carefully remove the ribs, place them on a foil-lined sheet pan, and brush with extra pineapple BBQ sauce from the slow cooker. Arrange ribs in a single layer so the sauce caramelizes evenly.

Broil at 425°F for 5–7 minutes until the sauce caramelizes and gets slightly charred. Visual cue: you should see glossy dark spots on the top edges of the ribs.

Garnish with chopped fresh cilantro and serve with extra pineapple BBQ sauce on the side. If using pineapple rings, add them for serving to bring extra tangy sweetness.