UPDATE
OFFICIAL Angular CLI https://angular.io/guide/creating-libraries
You can create an angular2 component library (with tests) and then use it in any number of projects
Then you can publish it on npm for public use. If you want to keep it private, you can read this https://docs.npmjs.com/creating-and-publishing-private-packages
Yes, many 3rd party angular2 components exist. Here are a few from valor-software https://github.com/valor-software/ng2-plans
If you don’t want to publish your library and still use it, you can create a mono repo architecture. There is a tool by ex-googlers called nx https://nx.dev/. You can create a library using it and can use it in your project https://nx.dev/latest/angular/tutorial/08-create-libs
Yeoman Generator for angular library https://github.com/jvandemo/generator-angular2-library