How to package a react application into an npm package for private use?

Question

npm

The crux of the matter is that I have a react application built on a bunch of other modules. It will have to work in other applications as a widget that can be imported from npm.
How do I pack all this?
Is there a need to add / remove additional files and how to prepare the application in general?
Will everything be fine if third-party modules are connected to me?
How to make a package private afterwards?
How to pass then parameters to your widget-component and how to process these parameters on the side of the component itself?
And if the application is created in create-react-app, should it be ejected or built (eject/build)?
Any advice, link would be very helpful, thanks.