When you have Multiple Approval Processes for an Opportunity and different Final Approvers who approve them depending on the amount on that opportunity, the Opportunity Owner doesn't know who is the Final Approver for an Opportunity.

This video will explain how to achieve this using a custom field and a Flow.

You can create a custom field called Final Approver with picklist data type (or any text field on your choice) and include all the final Approvers as the values for that picklist. We are going to set value to this custom field with in the flow.