How to setup purchase contract approval rule based on item category

Summary:

How to setup purchase contract approval rule based on item category?

Content (required):

The business wants to setup contract approval rule using contract type and item category as conditions. For instance, for purchase contract, if item category =A, then approval group 1; if item category = B, then approval group 2. Currently, I could not find relevant item/purchasing category in BPM condition browser in ContractApprovals task.

Version (include the version you are using, if applicable):

23C

Code Snippet (add any code snippets that support your topic, if applicable):