The standard for smokers or pellet grills is the 3-2-1 method. 3 hours at 225, then wrap in foil and juice again, for another 2 hours, then a final 1/2 to 1 hour open to get the crisp you want.
The wife and I like fall off the bone ones, so I do them 40-50 minutes in the Insta-Pot, then glaze with Sweet Baby Rays and grill for about 10 minutes on my gas grill. Comes out wonderful!!