I have some notes from doing it but its been a minute, the overview is:

• create your users in and out of the container with the correct ids
• edit the conf to pass through the dir and map the ids
• edit the subuid and subgid

The documentation on this kinda sucks because its not all in one place so if you find the first link you might get lost without the info in the second. I took me a few forum posts to find out about all the id mapping stuff and finally find the right page.

• https://pve.proxmox.com/wiki/Linux_Container#_bind_mount_points
• https://pve.proxmox.com/wiki/Unprivileged_LXC_containers

You can bind mount a directory on your pool into an lxc too. I do this with smb and a few other file/data services without issue but never tried omv. If containers work for you it might be the simpler way to go.

"I nearly lost my mother to the poison coming across our border“ sure sounds like lying to me. There’s clear omission of key facts leading people to the wrong conclusion.