For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mmanu84:php8:php84/openSUSE_Slowroll/home:mmanu84:php8:php84.repo
zypper refresh
zypper install php8
For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mmanu84:php8:php84/openSUSE_Factory/home:mmanu84:php8:php84.repo
zypper refresh
zypper install php8
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mmanu84:php8:php84/15.6/home:mmanu84:php8:php84.repo
zypper refresh
zypper install php8
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mmanu84:php8:php84/15.5/home:mmanu84:php8:php84.repo
zypper refresh
zypper install php8