Are you using the awesome Benji backup. Then check out this script to make restore of benji backups a piece of cake.
If you backup Proxmox VE KVM disks from Ceph storage with benji then this is a perfect match. If you are using benji backup with another infrastructure then you will be able to edit the script to your needs in minutes. Currently it is tightly cuppled to my backup wrapper for benji and PVE - pveSnapBackup. Contributions to make it more general purpose are welcome.
Automatically set up and mount a NBD device (default is /dev/nbd666) to gain file level access to your benji backups.
Restore your benji backup to a raw disk image file. You will need enough disk space on your backup host.
Restore a benji backup directly to its original CEPH storage pool.