You can now prevent public access on storage containers through policy as of July 2020.
https://docs.microsoft.com/en-us/azure/storage/blobs/anonymous-read-access-prevent
Here is a policy that facilitates enforcing this:
https://github.com/davidokeyode/charis-cloud-azure-policy/blob/master/storage/storage-account-public-blob/azurepolicy.json
HTH. 2020-July-20 By Jacky