Now, I tried with something like,
xzcat /path/to/image.xz | blocksync-fast -s - -d <dst_device> doesn't work.
blocksync-fast -s <(xzcat /path/to/image.xz) -d <dst_device> doesn't work either.
The reason this feature will be useful is, We can have compressed image archives, with unused spaces to be zero, The source image will be very tight. Without stdin support, We have to use a large tmp folder with a more time consuming step.
Thanks.