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?
Context
I write classes and packages from time to time.
Sometimes, we can find posts like Alternatives to the physics package or Physics replacement effort, where people discuss their own implementations that could be shared through a package or a class.
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.
tikzducks
apparently did that too: codereview.stackexchange.com/q/171782git pull
to get the latest updates. On the other side, I don't think that sharing the github repo link in a question here on TeX.SE may be appropriate, just to let people knwo that it exists. But you can always look for questions that may be answered by your package, and provide your input.