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; this helps the ribs stay tender. Pat the ribs dry so the rub clings evenly.

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

Whisk BBQ sauce, crushed pineapple with its juice, brown sugar, soy sauce, apple cider vinegar, minced garlic, and Worcestershire sauce in a medium bowl. Stir until the sugar dissolves and the sauce looks uniformly glossy.

Pour about 1/3 of the pineapple BBQ sauce into the bottom of the crockpot to form a flavorful base. Tip: keep the remaining sauce ready to coat the ribs later.

Place the ribs in the crockpot, standing them upright along the edges if needed, and cut the rack in half for a better fit. Nestle them snugly so they cook evenly and stay mostly upright.

Pour the remaining sauce over and around the ribs, making sure they are well coated. Spoon extra sauce into any gaps so the meat braises in the mixture.

Cover and cook on LOW for 7–8 hours or HIGH for 4–5 hours, until fall-off-the-bone tender and easily pulls away. During the last 30 minutes, you should see the sauce thicken slightly and look darker.

Carefully remove the ribs to a foil-lined baking sheet and brush with extra sauce from the crockpot. Aim for an even coating so the glaze caramelizes on top.

Broil at 425°F for 5–7 minutes until the sauce caramelizes and gets slightly charred. Watch closely so the edges darken without burning.

Garnish with chopped fresh cilantro and serve with extra pineapple BBQ sauce on the side. Add pineapple rings on top if using, right before serving for best freshness.