For a customer request, maybe the Role "IP SECURITY MANAGER" might be a solution, but therefor I need some additional information about the capabilities:

Is it possible to define rules to restrict access only to single custom attributes (like "Supplier" or "Cost") for objects and keep the remaining access to the object and structure open?

Example: Want to invite suppliers to my 3DEXP to work active on my project with full access but they should not see stored information (in custom attributes) like selected supplier for other parts or estimated prices.