Hi,
I think that you'll find some answer
there
:
There is no options for that. If you want to do it, you will have a lot of work:
1. You need to take some code from the file components/com_hikashop/views/product/view.html.php to load the data of the variants/characteristics in the listing and not only in the show.
2. You need to take some code from the file components/com_hikashop/views/product/tmpl/show.php to display the characteristics dropdown
3. You need to add all that in one of the listing_ files of the view product (it depends how you want to structure your code).
Hope this will help you a little.