Help confirm my plan

Hi all, I have an old custom-built NAS/server with a low-end 4-core AMD processor. Previously it was running CentOS to host Samba shares and I ran a few other simple things on it like Plex and a game server.

I recently updated it to use Proxmox to try to be more organized with how I was running services, but then I came across an older mini PC that has more processing power than the old machine, so now I'm thinking the old machine will become basically just a NAS.

Also, in case it's helpful to know, I am repurposing another old machine to be an OPNsense router and plan to learn more about VLANs, etc for better network security with all of this.

Here is my plan. Please let me know if this makes sense, or if there is an easier route:

• Install TrueNAS Scale onto the old NAS machine. Host the shares via SMB (for access at home via Windows machines) and NFS (for access by the compute node)
• Figure out a way to automate, via TrueNAS, the weekly backups I normally do to 2 rotating external drives. This is my "2" in the 3-2-1 backup strategy.
• Use TrueNAS' simple built-in options to backup important shares (pictures/home videos/etc) to Backblaze B2. I had previously set this up, on the CentOS box, but haven't had the time to figure out how to do this in Proxmox. This is my "1" in the 3-2-1 backup strategy.
• Put ProxmoxVE on the mini PC to act as a compute node. Host the VM/LXC directly on this machine, but attach to the NAS storage via NFS for data.
• Run Plex, Nextcloud and/or Immich, game server(s), and a few other things on the compute node.
• Possibly consider installing Proxmox Backup Server as a VM hosted from TrueNAS to backup the compute node configuration.

The questions I have are:

1. Should I stick with Proxmox on the NAS machine instead of switching to TrueNAS? In my head, by switching I'm leveraging what each system is really designed primarily for, but wondering if TrueNAS is over complicating this here.
2. Is PBS necessary in this setup, or should I just use Proxmox's default backup method since the main data will already be backed up via the NAS box? If I understand it correctly, I would mainly just be backing up VM/LXC config, which I could also learn about doing through GitOps?
3. If I do go with PBS, is it significantly better to go with a 3rd machine to run it bare metal, or is the VM approach "good enough?"
4. Am I over complicating anything else? Is there a more simple approach I should be considering here?

Thanks!