Why is my screen touch unresponsive, and power button not working?

You can remove it from rice anytime, it won’t make a difference to a water damaged phone even if you leave it in there forever, most times rice just adds damage to damage. No one can tell if the phone is salvageable without opening it, but at least the non working parts will have to be replaced and the phone should be properly decontaminated with ultrasonic cleaning before reassessing damage. Most professionals don’t work on liquid damaged phones unless it’s for data recovery, but you could try contacting a lab in microsoldering near you to have them look into the iPhone and advice on necessary steps and costs.