So far I always used sleep when closing the lid of my Notebook, was ok even though you risk that your battery runs empty and your system shutdown. Wanted to activate hibernate which then would also support hybrid sleep, what seem to be compareable with what Apple does to achieve a massive standby and short wakeup time on the MacBook.
During the Setup I already created a Swap Partition equal to the size of my Memory, so I thought this should all work out of the box, but didn't.
Found a Post on reddit (Archive: [1]) and a related Bug Report (Archive: [1], [2]), both contained contrary information. Based on Reddit the resume module would be missing in initrd and should be included. The Bug makes clear that systemd-hibernate-resume is used and _not_ the resume module that could be added by dracut.
I trust the Bug Report more, but adding resume=/dev/mapper/system-swap (Has to be the path to your Swap Partition and might differ) to /etc/default/grub didn't solved the issue. So I generated a new initramfs by running dracut -f, without modifying any config, afterwards hibernate and hybrid sleep were working.
grep resume /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT="splash=silent mitigations=auto quiet resume=/dev/mapper/system-swap" sudo grub2-mkconfig -o /boot/efi/EFI/opensuse/grub.cfg sudo dracut -f
No Idea why I had to rebuild the initramfs, should already be done (automatically) during the last Kernel Upgrade, anyway, I can now use hybrid sleep which looks actually very good so far. Roughtly 30 - 60 sec until sleep after closing the lid, resume just a few seconds, not really different to sleep as far I can see.