using the script with gz image

[zacny]

Hello. Is it possible to use this script with compressed version of an image. Let say, I have large capacity disc, but it is almost empty. When I do image in that way:
sudo dd if=/dev/sdb | pv | gzip > backup.img.gz
I get an image that takes up practically as much space as the data inside it.
Is it possible to shrink backup.img.gz file, end up with shrink-backup.img that is almost the same size as backup.img.gz.
Can I do this in a single command?

[Drewsif]

You can not, PiShrink uses other tools that do not support working directly from a compressed image so there is no way to do it currently.