libisofs6 from isv:Rancher:Harvester:ExtraPackages:v1.2 project
Select Your Operating System
Add repository and install manually
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/isv:Rancher:Harvester:ExtraPackages:v1.2/15.4/isv:Rancher:Harvester:ExtraPackages:v1.2.repo zypper refresh zypper install libisofs6