Adding an Item Restriction Layer to Custom Rules in Delivery Zones

It is a frequent occurrence that certain products within a supplier's catalogue have differing delivery lead times.

This request is to build a functionality that would allow you to distinguish such products with their own rule. The proposal is that the user would first select the supplier they would like to restrict (existing) and then this would unlock an additional field to stipulate certain items to restrict (if left blank, all items linked to that supplier would have the said rule applied)