For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Virtualization:containers/openSUSE_Tumbleweed/Virtualization:containers.repo
zypper refresh
zypper install lxd
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Virtualization:containers/15.6/Virtualization:containers.repo
zypper refresh
zypper install lxd
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Virtualization:containers/15.5/Virtualization:containers.repo
zypper refresh
zypper install lxd