Use sharepoint, office365, and Teams. It versions, it supports collaborative editing, no more mailing things around, and so on.
Of course one can't do a pull request with Office (non-geeks would struggle with the idea anyway) but live-editing of shared documents and version history is now built-in.
If two or more people open the same .docx/.pptx/.xlsx from a shared environment (Sharepoint/Teams/OneDrive), and then proceed click on Open in Desktop App (the browser-based apps are unpolished IMO), AutoSave is automatically turned on, and they're automatically thrown into live collaboration mode. This is the new norm in most enterprises that have Office365.
Most office folks require version history rather than version control -- not many are likely to need to branch, merge, pull, push -- and Office365 definitely supports the former. You can even have a threaded conversation about the changes in the document itself. -- when you add a comment, the chat sidebar opens. The back-and-forth comments are stored in the document.
Note: this is different from "Track Changes" in older version of office -- which still exists but is more for visual diffing. Version history only stores snapshots.