Sigh. It seems there is no simple solution for my needs.
I finally caught up and read this thread.
A lot of people talk about self-hosting as if it was a mountain. I don’t understand it. I self-host using QNAP and it’s really not that harder then learning a new OS. You go through the settings making it secure (disabling lot of networking options lol), set your firewall rules and download the apps you need (I never had to use docker). The only thing that truly was a pain is setting up a VPN for remote access until I learned the existence of tailscale which was like magic.
Is the gap from QNAP to TrueNAS that big?
It was a bit discouraging reading that thread. A bit like @overdrawn98901 said here. Many things I didn’t understand.
One thing grabbed my attention in the beginning though:
I researched this and it seems that this statement is mostly true as the community and the developers strongly recommend using an Intel‑branded NIC. The reason is that Intel Ethernet controllers have long‑standing, well‑maintained Linux drivers that are known to work reliably with the FreeBSD‑based TrueNAS Core and the Linux‑based TrueNAS Scale kernels.
So I tried searching for Intel NIC in the steam machine specs, but couldn’t find anything. I asked AI and it said the Steam Machines ship with integrated Realtek or Broadcom Ethernet, which may work but could require extra tweaking.
Is this true?
If so, I’d be again back to square one.
I guess I’d either have to go with a True NAS mini, but it’s so expensive. The other option would just be to use SteamOS (from steam machine) as my server and forget TrueNAS?
Still so confused on what to do. Halp. 
If you forget money, what’s the simplest way to achieve my goal described above with a FOSS solution (exception being Steam Machine because in the end it’s a PC).