We can use only JS Code which are not dependent on any of either React Native/ React.js library. Example - If you want to share code which uses React Native Async Storage then that will create issue in React.js - as React.js don't have that library. But yes whatever common code / pure JS code we can share across both apps.
I think you can share react native UI components for web, But you need to use react-native-web package.
example here necolas.github.io/react-native-web/
is there a way to reuse the reactjs code in react-native or react-native code in reactjs
We can use only JS Code which are not dependent on any of either React Native/ React.js library. Example - If you want to share code which uses React Native Async Storage then that will create issue in React.js - as React.js don't have that library. But yes whatever common code / pure JS code we can share across both apps.
I think you can share react native UI components for web, But you need to use react-native-web package.
example here necolas.github.io/react-native-web/
You can't share UI elements, but you can create custom hook and share that logic between component