My prime question is: is there a proper way/website to share a package or a class of our own?
If the question is too generic, I can try to refine it a little bit: what is the best way to get some alpha-testers for a new package or class before trying to share it on CTAN or similar?
I write classes and packages from time to time.
I doubt that the TeX - LaTeX Stack Exchange is the right place to post a link to a GitHub repository or similar platform. Also, I'm not sure that we can send something directly to CTAN (or any other stuff) without having some alpha-testers.