This is really specific to *nix operating systems, so I don’t know if this would be something that would be considered implementing support for.
My backup process is a bit more time consuming because in order to backup my VM images directly into Duplicacy, I have to create a image of the RAW block LVM into a physical file for each VM. Creating a file every night for a 1.2TB VM block device and then having Duplicacy make the snapshot is a lot of extra I/O. Would there be a possibility to add functionality for me to symlink the LVM device into the root Duplicacy directory and have Duplicacy read the contents of the device instead of me having to create a file for it to read from? This would be a lot faster then having to create a file every time I want to backup the device.