Add the meat, sugar, and rub to a large mixing bowl. Stir everything together until combined.
Tear sheet of aluminum foil off in a roughly 8x11" shape. You'll need 6-8 sheets, depending on the size of your patties.
Lay out a single sheet of aluminum foil. Grab some of the seasoned meat mixture, and press it into a patty roughly as long as your buns.
Using the back of a butter knife, press rib 'lines' into the patty.
Gently fold up the sheet of foil around the sausage patty, sealing to close. Repeat until all the meat's been used and shaped into patties.
Pour 2 cups of water into the bottom of your pressure cooker's liner and then add the trivet (or steamer basket) to the pot.
Add the packets to the trivet, layering them so they're semi-even.
Add the lid to the pot, turning to close. Make sure the vent valve is set to seal, and then press the manual button until it's on high pressure, and set the timer for 20 minutes.
Once the timer dings, let the unit naturally release for 20 minutes. Being careful, turn the vent valve to release any remaining steam.
Use tongs to remove the packets one at a time. Grease may very well leak out so I like to unwrap them on a plate. Use the tongs to transfer the patty to layered paper towels to drain off excess grease. Carefully discard the greasy foil, and repeat until all the patties are unwrapped and drained.
Brush each patty with a liberal coating of thick barbecue sauce. Serve on rolls with sliced white onions and dill pickle slices.