Hi,
Am I understanding correctly, that you are trying to host an NFS share in TrueNas and trying to mount it in Proxmox? Or the other way around?
To add an NFS share to Proxmox, you don't need to manually edit your fstab. In the webinterface, click on `Datacenter`->`Storage`->`Add`->`NFS`. All you need to do then is choose an ID name, ip and directory you want to mount.
Hope this helps