Stir vegetable broth and saffron together in a bowl.
Bring a pot of water to a boil; add dried porcini mushrooms and cook until mushrooms are reconstituted, about 1 1/2 minutes. Drain and finely chop the mushrooms.
Heat 2 tablespoons olive oil in a pressure cooker over medium-high heat. Saute onion in hot oil until onion is caramelized, about 10 minutes. Add rice; saute until rice is translucent, about 2 minutes more. Add garlic and 1 tablespoon olive oil to onion and saute until fragrant, 1 to 2 minutes. Transfer rice mixture to a stainless steel bowl that can fit inside the pressure cooker. Stir vegetable broth with saffron, mushrooms, wine, and salt into rice mixture and toss to combine. Cover the bowl with aluminum foil.
Pour 2 cups of water into the bottom of the pressure cooker and place the pressure cooker's metal rack in the base for steaming. Place bowl with rice mixture on top of the metal rack in the pressure cooker.
Cover the pressure cooker with the lid, lock the lid, bring the cooker to high pressure, and cook under pressure for 6 minutes. Release pressure from the pot according to the manufacturer's instructions. Remove bowl with risotto from pressure cooker.
Heat remaining 1 tablespoon oil in a skillet over high heat. Saute shrimp in hot oil until they are bright pink on the outside and the meat is no longer transparent in the center, 2 to 3 minutes. Stir shrimp into risotto.
