That’s true, if there’s no load then the difference isn’t much money.
I’m running a NAS, some game servers, a forgejo instance and a jellyfin server and more on my machine so it’s never truly idle and I forgot to think about that metric.

Ah right, that rings a bell. Proxmox and Ceph sounds like a perfect experiment for OPs hardware. :)
https://pve.proxmox.com/pve-docs/chapter-pveceph.html

Yeah, I focused on the I’m just looking for some fun experiments, projects part.
I wouldn’t use the machines for anything other than experimenting for fun, they’re power hungry too if counting per performance.

I would look into setting up a proxmox cluster with high availability on them and from there you can look into fun projects that you can run as proxmox vms or lxcs.
https://www.xda-developers.com/proxmox-cluster-guide/
https://pve.proxmox.com/wiki/High_Availability

edit: HA seems to require a shared disk, such as a SAN or NAS.

Running games on Linux:
Using the Heroic Game Launcher you can install GOG/Epic Games games with a simple click, Steam works pretty much the same in Linux as in Windows today.
There’s also Lutris that’s great for running local windows installers (downloaded game installers from GOG f.e.). I used Lutris when my wife needed to install the EA App to run Sims 4 as a usage example.

PLEASE NOTE
The exception is some games actively blocking non-windows (Fortnite) and others using Anti cheats that requires Windows to work.

Gaming on Linux links
Where I usually check if a game runs properly on Linux - https://www.protondb.com/
A site that lists games that doesn’t work due to anticheat - https://areweanticheatyet.com/
Game launchers for other storefronts than Steam:
https://lutris.net/
https://heroicgameslauncher.com/

Linux DE and Distros
If you want a desktop environment that is similar to Windows as default and uses the latest graphics protocols in Wayland and so on then look into KDE. As a bonus KDE is developed by a non profit based in Germany.
OpenSUSE is a distro developed by a german company that uses KDE as default - https://get.opensuse.org/tumbleweed/?type=desktop
Normally I recommend Fedora KDE as a distro but that is developed by Red Hat which in turn is owned by IBM which feels a bit contrary to “Buy European”.