In a blender jar, add the coconut milk, cilantro, jalapeño, scallion, garlic, and salt. Blend until smooth. (Or place these ingredients in a deep, narrow container and use an immersion blender to purée.)
Pour the sauce into the inner pot and add the water. Select Sauté and adjust to High heat. Bring just to a simmer, then turn the Instant Pot off.
Break up the noodles into 3 or 4 pieces and place them in the pot in a single layer as much as possible. Layer the shrimp and broccoli over the noodles.
Lock the lid into place. Select Pressure Cook or Manual, and adjust the pressure to Low and the time to 0 minutes. After cooking, quick release the pressure.Unlock the lid. Gently stir the mixture until the broccoli and shrimp are coated with sauce. Ladle into bowls and serve immediately.
Unlock the lid. Gently stir the mixture until the broccoli and shrimp are coated with sauce. Ladle into bowls and serve immediately.