Can this be frozen for later after being fully cooked?

The sauce itself can easily be made ahead and frozen, as can precooked rice. However, I would not cook the entire dish ahead and freeze it. Chicken tends to get chalky and chewy in the reheating process. Fortunately, once you have the sauce finished, the chicken will only take about 10 minutes to cook from raw in the Instant Pot. That would still make for a very quick meal, and the time it needs wouldn't be significantly longer than what would be required if it were all frozen. The chicken would certainly taste better though, if cooked from fresh rather than frozen.