How can we restrict users from viewing purchase orders created by other users by category?

Our client has many users with the "Self Service Receiving All Requisitions" role allowing them to receipt purchase orders on behalf of other users.

We are wanting to restrict the purchase orders most of these users are able to view and receive based on category they were raised under; for example we don't want most of these users to have access to purchase orders raised under sensitive categories such as legal fees.

Is there a known way to achieve this?

Seems that a similar idea has been raised in the past - https://community.oracle.com/customerconnect/discussion/791220/security-measures-for-restricting-access-to-purchase-orders-based-on-item-category?utm_source=community-search&utm_medium=organic-search&utm_term=purchasing+role+to+secure+by+category