Comment 3 for bug 1391955

The guest session allows potentially untrusted users to log in without a password and implies severely restricted privileges and confinement of the temporary guest user account (see https://help.ubuntu.com/stable/ubuntu-help/shell-guest-session.html).
The script that comes with lightdm is specific to Ubuntu with lots of details that that are different or do not apply to openSUSE (and the reason why it is in the debian/ directory), it's probably better to start from scratch than trying to adapt it. And creating and removing a temporary user is the easy part, the hard part is to make the guest account reasonably secure and to restrict privileges that regular local users have. That is, you would need to develop a custom Apparmor profile tailored for openSUSE and also custom PolicyKit policies for guest users.
That would require a lot of effort, time and knowledge on distribution details, PolicyKit, and AppArmor as well as ongoing maintenance since you'd need to keep on top of thing when paths, DBus interfaces etc. change. Guest accounts are not so much a feature of LightDM but the whole distribution which is probably why to my knowledge no other distribution than Ubuntu supports them.
At least I don't have the time and necessary expertise in AppArmor to implement and maintain this, so I'm closing this. If you do, feel free to work on this and you probably want to coordinate this with the security team.