Place the trivet in the Instant Pot inner pot and add 1 cup water.
Using a sharp knife or kitchen scissors, carefully cut lengthwise down the top of each lobster tail shell to the tip, cutting through the shell but not through the meat, to create a butterflied appearance.
If present, remove the dark vein along the back of each tail and any grit. Gently loosen the meat from the shell and pull the shell down so the meat sits on top of the shell.
In a small bowl, combine 1/4 teaspoon salt (or to taste), 1 teaspoon garlic powder, 1/4 teaspoon onion powder, and 1 teaspoon smoked paprika.
Sprinkle the spice mixture evenly over the exposed lobster meat.
Divide 2 tablespoons unsalted butter and place the divided butter on top of the two lobster tails (about 1 tablespoon per tail).
Arrange the 2 lobster tails on the trivet with the shells facing down and the meat facing up.
Close and lock the lid, set the steam release valve to SEALING, and pressure cook on HIGH for 1 minute. When the cook time ends, perform a quick release of the pressure.
Open the lid away from your face, use tongs to remove the lobster tails from the pot, and serve immediately.