Install the NordVPN client on Fedora Silverblue! Just download the install.sh, make sure you have a toolbox created and are in a sudo enabled account and then run the script.
The nordvpn rpm client does not install on Silverblue correctly as the rpm package contains files in locations that are immutable on Silverblue. So, the install adds the repo, and the key manually, and then installs the package and then uses rpm2cpio to unpack the rpm so that the correct nordvpn file structure is created. This is, of course, a hack, but it works well.
The script may probably be buggy as I haven't tested it properly yet, but it has worked for me. I will test it properly soon.