How to use HCM DFF for approval rules in requisitions and invoices?

Has anyone leveraged an HCM DFF on employee profiles to create approval rules or conditions that systematically define a hierarchy approval based on dollar amount or job level for requisitions and non-PO-based invoices? We aren't using position trees, and workforce data is not uniform, i.e., grade levels aren't consistent, and job level/reporting structure varies for each person.