Mine is sadly over an order of magnitude higher than this...

I am really struggling to parse this. What?

Hard drives are for capacity. SSD's are for performance. This has been settled for a number of years, and is why you see multiple levels of caching in front of any modern enterprise storage system.

If you need IOPS, you need SSDs. The days of getting IOPS from multiple hard disks have been over for a decade.

Shelves use almost no power; everything is in the drives themselves. I have a 60-bay JBOD that uses ~40W empty. That's for massive 1400W 208V-only PSUs, backplanes, etc. That said, the ~15 drives I have installed use quite a bit more, so I leave it off 95% of the time. Just fire it up, run a backup to it, shut it down.

As others have implied, you need to have something run on startup that will execute that IPMI tweak again.

In my case ESXi auto-starts my VMs, one of which is a docker VM and it auto starts a container that does the IPMI tweak (and monitors temps and adjusts and all that).

You don’t need to layer it this deep, but fundamentally you need things to auto-start on boot, including this.

It's not Thunderbolt - it's just a USB disk enclosure with the cheapest possible 2.5" hard drive - yes, a spinning rust hard drive. The only thing you get over something $100 less is it stacks nicely with the Mini.

I'd say hard pass. What might work better is an external powered enclosure for the M.2's, as that would reduce the power budget your Mini is trying to satisfy.

Best you’re probably going to be looking at is a Tesla card of some variant, and in a 1U without external power support it’s not going to be beefy. You’re not getting anywhere close to an RTX anything in that server.