I just moved off my running Fedora Silverblue to another hard drive (replacing a HDD with a SSD) and explained it in case other people needed it here: http://mildred.fr/quick-posts/2020-04-28-moving-fedora-silverblue-to-another-hdd/
There is a few things that I could not get right properly, especially recreating the GRUB configuration. I ran grub2-mkconfig from the chroot but I always had the error that it could not find the root device. I ended up manually modifying grub.cfg, but this is rather suboptimal. Is anybody able to make this work?