FrontDoor to App GW to app service via Private Link to auth to AAD- will this work?

Question

Hi All,

Trying to to set up this configuration so users can log in to AAD enabled app service. We have FrontDoor at the top level which in turns redirects to an App GW2 which then redirects to the privatelink IP of the appservice. We followed this write up but have had no luck yet perhaps because it does not take into account the app gw2 we have in between.

I can think of this architecture as something quite a few companies would want so it's a bit surprising not so much literature is found on it.
Anyway, any help is greatly appreciated, even a different design could be considered as long we leverage FrontDoor and app service via a private link.