Pip does not need a package to be public in order to install it at all, I’ve installed plenty of packages from tarballs and directories just fine. From the docs[0]

Install packages from:

- PyPI (and other indexes) using requirement specifiers.

- VCS project urls.

- Local project directories.

- Local or remote source archives.

Although I’m not quite sure how you’re using “for public use” in that sentence.

[0] https://pip.pypa.io/en/stable/reference/pip_install/#id19