Для openSUSE Tumbleweed запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/openSUSE_Tumbleweed/X11:LXQt.repo
zypper refresh
zypper install screengrab
Для 15.6 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/15.6/X11:LXQt.repo
zypper refresh
zypper install screengrab
Для 15.5 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/15.5/X11:LXQt.repo
zypper refresh
zypper install screengrab