I left the default index routes as is and used double navigation:

Eg: Route 1 which is nested, navigates to Route 2 which is an intermediary page at the root

Route 1 - nested - in app/(main)/logout

 const navigation = useNavigation();    

  useEffect(() => {
    // Redirect to the target view after 3 seconds
    const timer = setTimeout(() => {
      navigation.navigate('signout' as never); }, 2000);

Route 2 - signout at the root - in app/signout

  const navigation = useNavigation();
  navigation.navigate('index' as never); 

But please advise when this is fixed and addressed or other alts are available.