Since you can SSH into the running image you can just use rsync to clone the entire disk. Is there something you know that is being missed here ?

Every time I've cloned a Linux image from one infrastructure provider to another, I've always had to identify 5-10 locations where it was customized for the infrastructure. Typically finding those is a matter of reading log files and knowing how linux works. To me, that's "trivial" because it's something I've been doing for decades. It may not be so for other people.