So the capability to have a category dynamic page remains. Basically, if you construct the URL of a dynamic page this way mysite.com/products/{field}, the only thing that separates it being an item page from a category page is the fact of how many items have the same value in the field field.
On the other hand, if you want to show a page that lists all the categories, it seems that the old setup for dynamic category pages won’t in your case. You need start with creating a new collection “Categories”. Then, you need to implement a so-called master-detail setup. You can find out more here: https://support.wix.com/en/article/displaying-content-from-multiple-database-collections-using-reference-fields-4034931#displaying-filtered-information-master-detail .