How can I dynamically import GitHub repository inside another GitHub repository?

I'm setting my website page on GitHub pages, and I do have another repository with a webpage which is independent of my personal webpage. How can I make my personal webpage's repository dynamically import the code from the other repository?

I have already searched for submodules but I think they don't import the code dynamically, plus I only want a bunch of files of the second repository, not the whole thing.

I've seen also GitHub webhooks but I don't see the way I could do it.

The key is that I don't want to be adding manually the new changes on both of the repositories, I would like to do it only in the one which is not my personal webpage and let the code flows automatically to the webpage.