Yes, you can definitely use React Native to add a single view or user flow to your existing app. All you need to do is set up React Native dependencies and directory structure once and then keep adding to the React Native code. Of course, this integration must be done separately for all the platforms. As a business or process owner, you must compare the investment (both time and cost) required for adding React Native to the existing app and building a new app before making a decision. It’s best to consult with a React Native app development expert to reach the correct decision.