Writing an rpm isn’t difficult… is that a commonly held belief? Maybe I don’t know what I don’t know, but I’ve found wrapping my head around deb packaging much harder than rpms.
When I last wrote one I was very new to it and rpm.org (where most of the public docs on the format reside I guess) was down/abandoned. It looks like rpm.org and the docs are back now? I had a bunch of special requirements for the lib I was making and not having docs for the format, especially all the funny macros, was pretty frustrating.