Hello @a-ksekhon , Thank you for reaching out. I think I did not understand the question correctly can you please share your network diagram?
Azure Front Door requires that the backends are defined either via a public IP or a publicly resolvable DNS hostname. Members of backend pools can be across zones, regions, or even outside of Azure as long as they have public connectivity. So wherever your public IP is hosted the request will be forwarded to that end point.
Additionally if you want to add a different resource in Azure select Custom host as your backend host type. Please let me know if you have any additional concerns.