Openmediavault makes more sense overall but actually, I would like to someday expose the ruTorrent frontend. A platform that manages VMs by design is more appropriate for my use case.
What I did not understand is that Proxmox is Debian. Samba can even work on Proxmox directly, although that misses the point of the distribution.
It was actually simpler to get to work than I expected, although it took a long time to read up on and get everything documented correctly.
Documentation/How To Guide Link: How To Create A NAS Using ZFS and Proxmox (with pictures)
For Samba and related file sharing protocols, there is also this project called Turnkey Linux that automates the bulk of the work and just needs tweaking here and there to work correctly with people’s configs.