Heat olive oil in the pot of an electric pressure cooker (such as Instant Pot®) on 'Saute' mode. Add onion and garlic; saute until soft, about 3 minutes. Add celery and cook until bright green, about 2 minutes longer. Add potatoes, cherry tomatoes, and carrots. Stir to combine.
Place chicken slices on top of the sauteed vegetables. Pour coconut milk over chicken. Add fish sauce and allow liquid to come to a boil, about 5 minutes. Mix in water, frozen peas, curry paste, brown sugar, and crushed bouillon cubes.
Place lid on the pot and lock in place. Bring to high pressure according to manufacturer's instructions; cook for 12 minutes. Release pressure through natural-release method, about 20 minutes.