How to separate UI component library from applications?

Question

git

There are two react-applications, then there will be two more and they all use the same set of self-written UI-controls on react.
To avoid code duplication, the task is to isolate all controls into a separate library, and in applications, accordingly, add references.
I would like the code of this library to live its own cycle, i.e. this would be a separate git submodule or repo. So that it has its own bundler, with tests and other things. But I don't want to post it as an npm package to the public (the customer will not approve).
I heard / read that Facebook refers to its react not as an npm package, but using relative paths to a separate repository (maybe I'm wrong).
The question is how to organize it correctly? Are there any articles with step by step instructions?
Thank you!

Answer 1

npm can connect a private repository. ( rtfm )

{
  "dependencies": {
    "acme-ui-kit": "git+ssh://[email protected]/acme/ui-kit.git#v1.2.7",
  }
}

// EDIT: added explanations
Create a project, transfer all this UI module there.
Build it correctly, make it look like an npm package. Just don't publish it, but create a private git repository (on some bitbucket/gitlab/etc).
And then, in the necessary projects, connect this module in the way that I indicated above.