Waiter caller web app

Based on a friend's experience with a waiter caller system in Korea ( apparently every korean restaurant has it, something like this https://www.ebay.com/i/252379236990?chn=ps&_ul=MX&dispctrl=1 ) we thought about implementing the same idea with QR codes on restaurant tables that direct to a web app in your mobile phone in which you can call the waiter or the check. Perhaps also extend it to a mobile based ordering system ( order from a menu like uber eats but you are already on the restaurant) . We dont really have any experience in the food industry, we think that it may cut expenses for restaurant owners. Any thoughts appreciated !