I have been working on a shared folder that sync between agents (https://www.filestash.app/agents/). The control plane [1] handles pretty much all storages protocols / platform (S3, SFTP, NFS< SMB, ....), you add the controls / permission boundaries and everything is auditable + traces, and the sync client is at the edge [2] to sync the data it actually has access.

[1] https://github.com/mickael-kerjean/filestash

[2] https://github.com/mickael-kerjean/fdrive