For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:Geo/openSUSE_Tumbleweed/Application:Geo.repo
zypper refresh
zypper install postgresql15-postgis
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:Geo/15.6/Application:Geo.repo
zypper refresh
zypper install postgresql15-postgis
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:Geo/15.5/Application:Geo.repo
zypper refresh
zypper install postgresql15-postgis