Rub thighs with salt, pepper, and garlic powder; nestle into slow cooker with sliced onion, garlic cloves, and chicken broth to infuse savory juices.

Cover and cook on low for 6 hours (or high for 3½ hours) until meat is tender and shreds easily.

In a medium saucepan, whisk together ketchup, brown sugar, apple cider vinegar, Worcestershire, smoked paprika, and chili powder until smooth over medium heat.

Let sauce bubble gently for about 10 minutes, stirring occasionally until it thickens into a glossy, deep-red glaze.

Transfer cooked chicken to a cutting board, discard onions and broth, then shred the meat with two forks until bite-sized pieces form.

Return shredded meat to the slow cooker or pot, pour in prepared BBQ sauce, stir until coated, and simmer on low for 5 minutes.

Toast buns until golden, pile on warm pulled chicken, add optional coleslaw for crunch contrast, and enjoy immediately.