Para 16.0 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:dfaggioli:devel:SLE-15-SP7/16.0/home:dfaggioli:devel:SLE-15-SP7.repo
zypper refresh
zypper install qemu-guest-agent
Para 15.7 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:dfaggioli:devel:SLE-15-SP7/15.7/home:dfaggioli:devel:SLE-15-SP7.repo
zypper refresh
zypper install qemu-guest-agent
Para 15.6 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:dfaggioli:devel:SLE-15-SP7/15.6/home:dfaggioli:devel:SLE-15-SP7.repo
zypper refresh
zypper install qemu-guest-agent