Can you use a branch as a library?

I want to create a branch of a library.

I then want to use components from the library branch, in another file.

Once the project is live, I would then merge the library branch back into the main file.

This is a way to manage work in progress changes to a component that are used in a project, and then a way to make that change live, once the project goes live.

The answer is no. This is a shame as is a common workflow pattern.