Just fyi - running TrueNAS with zfs as a VM under Proxmox is a recipe for disaster, as me how I know.

Zfs needs direct drive access, with VMs, the hypervisor virtualizes the adapter which is then passed through, which can mess things up.

What you’d need to do is buy a sata/sas card and pass the whole card through, then you can use a vm.

It honestly probably is