Interesting problem... How to use Purchasing category hierarchies without using Purchasing?

Summary:

We currently are licensed for Contract Management and PIM, only only have very limited license for Procurement. We would like to know of any creative solutions to have some kind of hierarchy functionality by using the Procurement Functional Catalog without punchouts or other higher-level procurement functionality.

Content (please ensure you mask any confidential information):

We would like to use UNSPSC category hierarchy at the Procurement Functional Catalog level, but we can only have 1 level. So our catalog must have the leaf-level categories defined (1000s of them). At the Supplier profile level, we want to use the Supplier Product and Services categories.