Hi Henry , You need to replace the entire UI with Flutter code in Dart programming language - https://flutter.dev/docs/get-started/flutter-for/android-devs#how-do-i-lay-out-my-widgets-where-is-my-xml-layout-file and for REACT you need to write first in React Native with using your own view - https://medium.com/47billion/how-to-develop-android-ui-component-for-react-native-fddd141f5ae4 and then migrate it to Android APK. Hope this answers your question. You can read this blog to better understand these 2 frameworks - https://www.simform.com/react-native-vs-flutter/