It is weird (and that’s why I asked).
Your disk is using legacy MBR partitioning rather than GPT partitioning. This is unusual for a system that is booting with UEFI.
In any case, here is how I would proceed.
Step 1: Make sure that secure-boot is disabled in BIOS settings. You may have already checked this.
Step 2: As root, edit the file “/etc/default/grub”. Check to see if there is a line:
(or similar – the quoting could be different). If there is such a line, then change that “true” to “false” and save the changed file.
Step 3: Run Yast bootloader.
There should be a box labeled “Boot loader” which says GRUB2 for EFI.
Change that to “GRUB2”.
The remainder of the screen should then change. And, with those changes:
Check the box: Boot from Master Boot Record.
Uncheck all of the other checked boxes.
NOTE: If what you see on the screen does not match what I am describing, then click “Cancel” instead of OK, and abort Yast bootloader (and tell us what you see that is different).
Then reboot. There should now be a Windows entry in the menu, but it probably doesn’t work. That’s because your system will probably still be using UEFI booting instead of legacy booting. You can check that by booting into openSUSE (which still should work) and running:
I’ll stop here for now until I get feedback on what is happening. You probably then have to delete the UEFI boot entry, so that it will revert to MBR booting. We can get to that step later.