Season the chicken with garlic powder, onion powder, salt, and pepper.
Heat olive oil in a skillet over medium heat.
Brown the chicken on both sides for about 5 minutes.
Transfer chicken to a slow cooker or Instant Pot.
Add barbecue sauce over the chicken.
If using a slow cooker, cook on low for 6-8 hours.
If using an Instant Pot, seal the lid and cook on high pressure for 25 minutes.
Once cooked, shred the chicken using two forks.
Mix the shredded chicken with the remaining sauce in the cooker.
Serve the pulled chicken on hamburger buns topped with lettuce, tomato, and pickles.