If working with a rack of ribs, slice ribs in between bones to create separate pieces. Place ribs on a sheet pan.
In a small bowl, stir together salt, smoked paprika, chili powder, onion powder, brown sugar, and allspice. Sprinkle over ribs to coat evenly. Refrigerate 2 hours or overnight.
Add beer, apple cider vinegar, and liquid smoke to a 6-quart Instant Pot Instant Pot; place trivet in Instant Pot. Stack seasoned ribs on trivet.
Place top on Instant Pot; twist to seal and lock. Turn Steam Release Valve to “sealing.” Set Instant Pot to cook at High Pressure for 30 minutes.
After cooking is complete, let pressure release naturally (approximately 15 minutes). After that, manually release the pressure by turning the Steam Release Valve to “venting.”
Carefully open Instant Pot lid. Remove ribs; place in a large bowl. Add barbecue sauce; gently toss to coat ribs.
Preheat a grill to medium-high heat or set oven to broil. Cook ribs until just charred, about 3 minutes per side. Serve with additional barbecue sauce, if desired.