Not sure what you mean about "providing an S3 or Azure storage Path".
But ... see you have linux (/var/www/) a clue ... and thus can do this.
mount the S3 or Azure storage from the operating system. S3 is probably linux so I'll use that in example.
example: /mnt/s3bucket in the OS. Readable/writable by web service user.
In moodledata/repositories/ do a symlink called s3bucket that points to the s3bucket mount point.
In Moodle Admin File System repos, setup a local file system named s3bucket and select the s3bucket.
My choice of ''dark side' is Google ... got a Google Bucket (1TB) that I have mounted from command line on a Rackspace server (running multiple 3.x versions of Moodle) as well as a Google Compute Engine instance (running only one version of Moodle).
Handy ... can backup courses from any of the moodles into directories of the bucket and those show up on all instances.
'SoS', Ken