Rinse brown rice under cold water, drain, and add rice, water, coconut milk, sugar, vanilla, cinnamon, nutmeg, and salt to the inner pot of your Instant Pot.
Close the lid and turn the knob in the Sealing position. Press Manual and pressure cook on high for 30 minutes.
After the rice pudding is cooked, allow the Instant Pot to release for 20 minutes naturally, then use the quick-release method to release the remaining steam.
Open the lid, stir the rice pudding, add vegan butter and raisins, and stir. If your rice pudding is not thick enough, Press Saute and cook, stirring until it reaches the desired thickness.
Serve your rice pudding hot or cold.