Using PO workflow according to a budget

Hi , how can i setup a PR or PO workflow in d365F&O so that i can manage a condition where i need to route my requisition or PO to a manager for a specific budgeted product. If there is budget then the workflow will go to A person; if no budget then the workflow will go to B person.
Thank you

How you are identifying that this item has budget?

In fact I need to setup my WF so that based on a specific reason i put on PR ; Approver will be my report To who has different approval amount depending on the reason choose. Hierarchy will be used and Approver should have different amounts depending on the reason code used.