If I understand the problem correctly it has a pretty simple solution that I have done before. Make a new partition on the destination and dd if=/dev/diskAsB of=/dev/diskXsY
where A is the source disk and B is the source partition and X is the destination disk and Y is the destination partition. You may have to run fsck on the destination afterwards and maybe a gpt repair tool.
Honestly though, since it’s an ext filesystem, if it were me I’d just mount the source and dest and rsync.
For some of us, finding ways to cheat IS the game.