I solved this by using a VPD policy to generate the predicate on the fly. so I am using an OLS policy together with a VPD policy on the same table.

what I had hoped for was using just an OLS policy and provide a SQL function for the predicate option/argument when applying the OLS policy to a table such that this function is called when the OLS policy is being enforced (meaning that the predicate would be generated on the fly based on user session).

Pablo, thanks for you replies.