For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ojkastl_buildservice:Branch_systemsmanagement/openSUSE_Tumbleweed/home:ojkastl_buildservice:Branch_systemsmanagement.repo
zypper refresh
zypper install pulumi
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ojkastl_buildservice:Branch_systemsmanagement/15.6/home:ojkastl_buildservice:Branch_systemsmanagement.repo
zypper refresh
zypper install pulumi