well, there are many things to consider. TrueNAS’s ZFS is memory hungry, and is best used on it’s original BSD. Also, you may need SMART directly in your NAS, then you’ll need to PCI passthrough the disk controller if you are on proxmox. With that said, either directly running TrueNAS Scale or TrueNAS Core on proxmox isn’t ideal. Also, running database storage over NFS has great disadvantages, so I would really advice against going proxmox+truenas route.
IMO, a mature NAS system is only useful as it is designed to be: bare metal system for your disk management. If you really wanna ZFS, then use TrueNAS Scale. If you are a guru and can or are willing to setup things yourself and doesn’t care about RAID5/6, just use regular linux + docker/podman + btrfs.