Adding top level folder name to metadata

[SethHorwitz]

I have a group of users with a large library, comprised of more than 1000 top-level folders with client names.  (Under each top level folder, there may or may not be subfolders.)  I've been working with them to add metadata to be applied to a subset of documents from a variety of folders, and have created a view to "show all items without folders" to display documents independent of their folders.  Unfortunately, this view "loses" the client name from the top-level folder in which the document is found.

I would like to add a metadata column to the library that displays the name of the top-level folder in which the document is stored (and not any of the intermediate folders, if there are any).  What are my best options?

Thanks,

Seth

[#2]

@SethHorwitz, I made a screenshot for a document set I used once in a site ... you can create documents sets, which are a kind of folder, but with metadata columns. They vanished from SharePoint a couple of years, now they back again in modern SharePoint online. Here is an article about doc sets in modern SharePoint Sites: Document Sets In Modern SharePoint Libraries (c-sharpcorner.com)

With doc sets you can have the customers on the top and for each doc set the projects and their files within. 

Hope this helps, greets from Eva.