Thin clients are also solidly good as container hosts. I've used HP T630s and Wyse 5070s in place of RPis during the great pi shortage with good results. You know something is fucked when you can spend less money on a J5005 with 8gb RAM than you do on a Pi 4.

I've had good luck running more intensive loads on more recent models of these systems, say 3 to 5 gens old ... multiple desktop OSes running concurrently on Proxmox, etc. The "1 liter" class of PCs is really quite capable these days!

So the big gain you’ll likely see is bang/capability for the money. If you’re careful and wait for a deal, can usually find 1L boxes for like $50-75. Get a cheap m2 ssd (and back up your confs regularly if you’re not running raid z2). The nic is going to be anywhere from about 30-70, but you’ll need to do your research on exactly what capabilities the thing you’re buying has (for example: I had a false start initially, because the RJ45 10G nic I found couldn’t negotiate at 2.5G (what I’m running now), and it’s actually pretty hard to find a 2.5G enterprise nic. Make sure the nic is intel, too - none of that Realtek crap, which is less performant and often has stupid driver crap you have to deal with under Linux and BSD (pfSense). You may want to spend a few extra bucks and get the Lenovo external pcie mount plate/bracket for aesthetics/“don’t stick your fingies in here”, and you will need an adapter for Lenovo’s proprietary PCIe-but-not-a-standard-PCIe-port thing.

i5 8500T. I don’t recall exactly what the power draw is, but iirc it’s in the 20-30w range - admittedly a bit high, but that’s likely due to the old LSI nic in there which is technically an enterprise-grade card, and not terribly power efficient. Nonetheless, works great, full 10G speed, no thermal issues in the last few months I’ve been running it (in the summer, so I should be totally fine in the winter).