Place a steamer basket inside of a 6-quart or larger Instant Pot. Pour in the water and then add the Brussels sprouts. Lock the lid and make sure the vent is set to seal. Cook on high pressure for 2 minutes. Once done, manually release the pressure until all the steam has been released and the lid has unlocked. If you allow the pressure to release naturally, the sprouts will become mushy.
Carefully open the lid, remove the steamer basket with the sprouts and set aside. Drain the liquid from the inner bowl and return to the pressure cooker. Press the sauté function and add the bacon. Cook, stirring often, until the bacon has browned. Stir in the shallots and garlic and cook for 1 to 2 minutes, or until softened. Add the Brussels sprouts and sauté for a minute longer. Season the sprouts with lemon juice, salt and black pepper. Turn off the machine and serve immediately.