Rinse the rice and the beans under running water. You will need to lightly toast the mung beans and the rice. You could either toast them in a pan or in the Instant Pot on saute, lightly toast the rice and the beans until the beans become aromatic but don't change in colour. Make sure that you keep stirring the rice and the mung beans often as you toast them so that they don't get burnt.
Add water to the Instant Pot or your pressure cooker, then pressure cook on high for 15 minutes. Do a quick release, then check the consistency of the mixture. You can add a little bit of water if it feels too dry.
Using the back of a wooden spoon or a potato masher, mash the mixture lightly.
To make a jaggery syrup or a brown sugar syrup, in a saucepan chop up some jaggery and add water. on low heat, let the jaggery melt completely until you get a syrup. If using brown sugar, then just do the same.
Mix in the rice-mung bean mixture, ground cardamom, and nutmeg if using. Followed by the syrup, mix well and check if some more boiling water needs to be added.
Mix in toasted cashews, desiccated coconut, and raisins if desired and serve.