For openSUSE Factory ARM run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mbrugger/openSUSE_Factory_ARM/home:mbrugger.repo
zypper refresh
zypper install mlxbf-bootctl
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mbrugger/15.5/home:mbrugger.repo
zypper refresh
zypper install mlxbf-bootctl
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mbrugger/15.4/home:mbrugger.repo
zypper refresh
zypper install mlxbf-bootctl