Place the chicken in the slow cooker, then pour over the BBQ sauce or broth, ensuring the meat is mostly covered. Add sliced onions and minced garlic on top.
Cover and cook on low for about 4-5 hours, until the chicken is tender, fragrant, and easily shreds when pressed with a fork.
Remove the chicken from the slow cooker and transfer to a large bowl. Use two forks to shred the meat into bite-sized pieces, feeling it become soft and moist.
Drain any excess liquid if necessary, then toss the shredded chicken with the cooking juices for extra flavor and moisture.
Toast the buns until golden and slightly crispy, either in a skillet with a little olive oil or under the broiler.
Pile the warm, shredded chicken onto the toasted buns, then add optional pickles or coleslaw for texture and flavor contrast.
Finish by adding any desired condiments, then serve immediately, enjoying the tender, flavorful chicken with a satisfying bite.