Add the potatoes, sausage and corn to the liner of the instant pot. Add the onion if you prefer really soft onions, or add with the shrimp for more texture to them.
Mix together the chicken broth, hot sauce and 3 tsp of old bay seasoning, then pour into pot. Make sure your silicone ring is fitting snuggly, then attach lid to pressure cooker. Close vent to sealed position, cook on HIGH pressure for just 5 minutes, followed by a quick release of pressure (once timer has counted down the 5 minutes open valve to release pressure).
Quickly add in the frozen shrimp and cover the lid, closing the valve again. Cook on HIGH pressure for just 1 minute, followed by a quick release. Drain any excess liquid from pot if desired.
Pour mixture into a large, rimmed tray. Combine melted butter, garlic powder and remaining 1 tsp of old bay seasoning and drizzle over corn, potatoes, shrimp and sausage. Garnish with freshly chopped parsley and serve with lemon wedges. Enjoy!
*If using a smaller size shrimp (medium is the smallest I would go) - reduce cook time to 0 minutes after adding the shrimp. The pressure cooker will still come to pressure and then you will release the pressure immediately.