For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/openSUSE_Tumbleweed/X11:LXQt.repo
zypper refresh
zypper install xdg-desktop-portal-lxqt
For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/openSUSE_Slowroll/X11:LXQt.repo
zypper refresh
zypper install xdg-desktop-portal-lxqt
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/16.0/X11:LXQt.repo
zypper refresh
zypper install xdg-desktop-portal-lxqt