how to place a listview inside a SingleChildScrollView but prevent them from scrolling separately?

You could use your first widget-tree and apply the following changes:

1. In every ListView and GridView set shrinkWrap: true. This fixes the error message you were getting.
2. In every ListView and GridView set physics: NeverScrollableScrollPhysics(). This disables the scroll on them and new you can only scroll on the SingleChildScrollView