This is in progress for Azure CDN from Microsoft.
-Max G [MSFT]
Due to various technical limitations, the first iteration of the customer-owned domains functionality will not be available for a few more months. We will provide an update as soon as we can get a more specific ETA.
An error occurred while saving the commentDavid Starling commented
Any ETA? Been over a year since Microsoft's last status update
We have a sample for this use case here: https://github.com/azure-ad-b2c/samples/tree/master/policies/invite
Let us know what you think and if this fits your use case.