Set an Instant Pot® to saute on the medium setting (see Cook's Note). Chop the shallot and garlic. When the pot is hot, add 2 tablespoons butter, then add the shallot, garlic and a pinch each of salt and pepper. Cook, stirring, until softened, about 3 minutes. Stir in the rice and thyme sprigs and cook until the rice is toasted, about 3 minutes. Stir in the wine, scraping the bottom of the pot, and cook until evaporated, about 30 seconds. Turn off the saute function.
Stir the clam juice and 3 cups hot water into the pot. Close the lid and turn the steam valve to the sealing position. Set the pot to cook on high pressure for 5 minutes. When the time is up, turn the valve to the venting position and release the steam completely. Be careful of any remaining steam and unlock the lid.
Season the shrimp with salt and pepper and add to the pot. Stir in the peas. With the pot still turned off, close the lid and let the shrimp cook through, about 5 minutes.
Add the parmesan and lemon zest to the risotto; stir in the remaining 2 tablespoons butter until melted. Add a few dashes of water to loosen, if necessary. Discard the thyme sprigs. Divide among bowls. Top with lemon zest and serve with lemon wedges.
Settings may vary on your Instant Pot® depending on the model. Please refer to manufacturer's guide.