Prep the slow cooker: Lightly spray the insert or use a liner to make cleanup easier.
Layer the aromatics: Scatter sliced onion and minced garlic in the bottom of the cooker.
This prevents sticking and infuses flavor.
Add the chicken: Place chicken breasts or thighs on top. Season both sides with a little salt and pepper.
Mix the sauce: In a bowl, combine BBQ sauce, pineapple with its juice, soy sauce, ginger, vinegar, and smoked paprika. Stir to blend.
Pour and cook: Pour the sauce mixture over the chicken.
Cover and cook on Low for 4–5 hours or High for 2.5–3.5 hours, until the chicken is tender and easily shreds with a fork.
Shred the chicken: Transfer the chicken to a cutting board and shred with two forks. Return the shredded chicken to the pot and stir to coat in the sauce.
Adjust thickness (optional): If you want a thicker sauce, stir in the cornstarch slurry, switch to High, and cook uncovered for 10–15 minutes until glossy and slightly thickened.
Taste and finish: Taste and adjust salt, pepper, or a splash of vinegar for brightness. If you like heat, add a dash of hot sauce or red pepper flakes.
Serve: Spoon over steamed rice, stuff into slider buns with slaw, or fill warm tortillas and top with green onions and cilantro.