Whisk BBQ sauce, apple cider vinegar, honey, and garlic powder together in a 6-quart slow cooker until smooth. Season chicken on both sides with a pinch of salt and pepper, then nestle the chicken into the sauce, turning to coat.

Cover and cook on low for 6 to 7 hours or on high for 3 to 4 hours, until the chicken shreds easily and reaches an internal temperature of 165°F.

Transfer the chicken to a cutting board and shred with two forks. Return the shredded meat to the slow cooker, stir well to coat in the sauce, and let sit on warm for 5 minutes. If the sauce needs thickening, cook uncovered on high for 10 minutes, stirring occasionally.

Pile the chicken onto toasted brioche buns with coleslaw, or spoon over rice and serve immediately.