LXC and USB drives will give you problems. It'd be easier to run OMV as a VM and then pass the USB through in Proxmox web UI.
Proxmox
Proxmox VE is a complete, open-source server management platform for enterprise virtualization. It tightly integrates the KVM hypervisor and Linux Containers (LXC), software-defined storage and networking functionality, on a single platform. With the integrated web-based user interface you can manage VMs and containers, high availability for clusters, or the integrated disaster recovery tools with ease.
Is the VM using the USB drive at the same time?
No, I have an extra USB drive to test it out.
FWIW, I ended up just using a VM when probems like this would inevitably crop up with LXCs running software which goes too far off the garden path so to speak. My knowledge is a lil dated as I set most of my shit up about 2 years ago but at that time I got the distinct impression that LXCs were not fully-baked for running a number of things. Mostly I absorbed that info from reading the Proxmox forum. I'd love to hear if it's improved since 2021.
No idea. I'm new to proxmox and Linux by about 2 weeks, so I'm mainly just trying to learn. I figured since the tteck script sets up a LXC, it would be possible, but I can't really find any record of someone else doing it.