Use SharePoint for yearly employee performance reviews.

I've done something similar, but using SharePoint lists. What I did was set the permissions on the lists so that users could only view their own items, then used the org hierarchy to set the row-level security in Power BI (users can see records for people reporting up through them using PATHCONTAINS()). I would not do this with files if you can avoid it, because then you have to set actual file permissions and it's a mess (whereas with lists you can just do dynamic row-level security).