Place the chicken breasts in the slow cooker.
In a medium bowl, combine the barbecue sauce, chicken broth, chopped onion, minced garlic, apple cider vinegar, brown sugar, smoked paprika, chili powder, salt, and black pepper. Stir until well mixed.
Pour the sauce mixture over the chicken breasts in the slow cooker, ensuring they are well coated.
Cover and cook on low for 4 hours, or until the chicken is tender and easily shredded with a fork.
Remove the chicken breasts from the slow cooker and shred them using two forks.
Return the shredded chicken to the slow cooker and stir to coat evenly with the sauce.
To assemble the sliders, place a generous scoop of the shredded BBQ chicken on the bottom half of each slider bun.
Top each with a slice of dill pickle and a sprinkle of shredded cheddar cheese.
Place the top half of the slider bun on each and serve immediately.