I saw on documentation that KDE has their libraries open and such and was wondering if I could use them to make my own software with KDE libraries and code? (If they are open to use?) Im not saying I want to make KDE software for the official program list but to use for myself to make my own software.
If it’s possible, any resources other than documentation that I could reference to ? (To learn more and improve my knowledge?)
Yes you can. That’s how the library ecosystem in general works, you don’t need to make a KDE app to use KDE libs. Just mind the fact that KDE libraries are (mostly) LGPL.
It’s like using any other library. You find and link it in CMake (or Meson), include it in code, and use it as specified in api.kde.org. A good way to check how an API is used is by searching for existing code in KDE projects or on LXR.