I just purchased and installed the Product Finder Extension for a client. I have a number of other clients who are interested in the same kind of plugin for Woocommerce; however, they are put off by one issue with the plugin that makes it unusable for their sites.

The product categories in the category drop-down do not display anything to represent their place in a hierarchy. The categories are all just listed in the drop-down with nothing to signify which parent category they belong to. My clients say that it's confusing to users especially for stores that have parent categories with similar or the same subcategories.

To fix this, you'd need to list the parent categories then their child categories in the drop-down something like this:

parent category 1
-- subcategory 1
-- subcategory 2
-- subcategory 3
parent category 2
-- subcategory 1
...

If you would modify the Product Finder Plugin to do that, you would make the Plugin useful for many more sites and sell a bunch more of them.