> Network drives mean no local retention

Technically speaking, Windows does support client-side caching on network drives. I've used it in the past for a highly limited number of users (read: me, on a personal share) and it works kind of like OneDrive/Dropbox/other cloud platform. But it's really rough and doesn't handle conflicts well.

https://learn.microsoft.com/en-us/iis/web-hosting/configurin...