OpenSUSE's image writer for windows doesn't seem to exist anywhere any longer. I've scoured around their pages and can't locate a working build any longer. Many years ago I've seen what installing KaOS with a different image writer like Etcher could do (It didn't work) so how can I find either a working version of that Image Writer for windows? Or is there a different bootable USB writer that I can use instead with confidence?

If image writer is no longer available, then no other option than to update the docs and recommend Rufus with dd only.
It has been mentioned several years now that Rufus with the dd option probably works fine, just no feedback at all from actual windows users to justify having it in the docs.
Do not try to use Rufus in the default mode, it will fail to install with it, select the dropdown menu to use dd.