You can use `useAuthenticator` hook to access current signed in `user`. If no user is authenticated, it'll return `undefined`.

```jsx
import { View, Text, Button } from 'react-native';
import { useAuthenticator } from '@aws-amplify/ui-react-native';

const Home = () => {
  const { user, signOut } = useAuthenticator((context) => [context.user]);

  return (
    <View>
      <Text>{`Welcome, ${user.username}!`}</Text>
      <Button onPress={signOut} title="Sign Out" />
    </View>
  );
};
```
