As I understand, you're developing a global module that extends the vendors functionality. I discovered the inconvenience of NopCommerce when adding new products. In the case of a large number of categories, their choice is very inconvenient. When vendor manually adding goods, he must scroll through the large list. Tell me, are you planning to add the function of setting the visibility of unnecessary categories with subcategories in the new module?
Thank you for answer. With your permission, I will show some more impudence. :) For professional work with vendors, NopCommerce lacks the function "vendor status" in terms of the site's administration. Rating of the vendor by customers is very good, but rating of reliability and sufficient legal verification of the vendor is no less useful thing. Proposed status of the vendor (as example): "unverified", "verified", "reliable".