[dnanian]

While you can use images if you must, you can't use read-only images for APFS. In general, as I've said in detail elsewhere, I would discourage the use of images, and as of 10.15.5, it won't be possible to create images of Catalina volumes (we found significant reliability issues).

I strongly encourage you to move away from images and to something more along the lines of iSCSI volumes, if you need to work over a network, or direct-to-drive backups.