On a app with many collections, it's common have a deep navigation, with many steps to achieve an article and many steps to get back for home screen too.
It would be great if, while the user starts his navigation deep and deeper through collections, the top bar could indicate not just a back button, but also a 'home' or 'menu' button for the user get back to the main page without need to tap back, back and back many times to achieve the home screen. Here is an example: