To prepare the chicken, pat it dry and use 5 lbs of bone-in, skin-on chicken thighs. Arrange them on a wire rack over a baking sheet and generously sprinkle with 1 tbsp of salt and 2 tbsp of chicken rub. Let the seasoned chicken sit in the fridge for 1 hour before grilling.
Prepare your pellet smoker for a temperature of 350°F, and make sure to clean and oil the grill grates.
To smoke the chicken thighs, place them on the cooler side of your grill with the skin side up and close the lid. Cook for 35 to 40 minutes or until the thighs reach 180 to 190°F, rotating them halfway through for even cooking. After smoking, remove the chicken from the grill and increase the heat to sear.
Lightly brush the chicken with 1/2 cup of BBQ sauce. In batches, sear the chicken skin side down until it's lightly charred and the skin is crisp, then flip and cook for 2 to 3 minutes longer. Repeat with the remaining chicken thighs.
After cooking, remove the chicken from the grill and place it on a foil-tented platter to rest for 5 minutes. Serve the chicken hot, and if desired, offer additional BBQ sauce on the side.