Set the pressure cooker to "Saute" and add the olive oil to the bottom of the pot. Heat the oil until simmering then add the onion. Cook until the onion has softened and is starting to brown. Add the rice and garlic and stir until the oil is absorbed, then stir in the white wine. Let the wine simmer for 12 minutes, then add the chicken stock. Zest the lemons and set the zest aside, then juice the lemons and add the juice to the pot. Close and lock the lid, making sure the pressure gauge is set to "Airtight". Cook for 6 minutes. When the time is up, carefully quick release the pressure gauge, using tongs or another utensil to move it to "Exhaust", making sure to keep any exposed skin away from the pot immediately and scrap into a large bowl. Add the lemon zest, grated parmesan and salt stir to combine. Stir hot.