Show product only, not categories

Following on from this, is there a way to show only products of a category instead of sub-categories and products?

We have category Parts with about 20 sub-categories. When using filter cat:parts, we get the sub-categories followed by the parts. We prefer to have categories on a separate tab, which we have with cat-list, and just products categorised as parts on the Parts tab.

Any way to achieve this? If not, perhaps consider a “prod:cat” filter which just lists products in the specified category. Or provide a filter hook where we can adjust the query to list products only.