Hi,
It's possible.
You need to do two things:
- configure your menu item to be of the type "products listing" instead of "categories listing".
That way, you'll only get the products displayed.
- configure a new module instance of the type "HikaShop content module" via the Joomla modules manager to display the listing of your categories and configure it to appear on that menu item only, and for the position of your template at the top of the main area (so just above the products listing).
The look will be the same and it will work the same, but the module will still list the categories even when you access a category.