For some reason my management is 100% against one drive. Instead each of our departments has there own SharePoint site and inside of that site each user has there own document library that's locked down to only them. The question I have is there anyway to have a link in the navigation pane that states "my personal folder" and when the person click it it will know somehow there name and direct them to the correct document library. Im trying to avoid having a big list of names with links in it. Each document library is names "Department Name + username"
Note that programmatically updating navigation elements is not supported for SharePoint Online modern experience. If you plan to put dynamic URL in navigation, that will not work for modern Navigation/Quick Launch.
Here is a reference on classic experience: Dynamic Navigation Link bar URL to reference current site.
And how to get current user: Sharepoint Online: Get Department of current user using REST API.