Building my own libre Gaming PC with mixed AMD/NVIDIA

Recently I found two articles on Boiling Steam that I find interesting:
https://boilingsteam.com/i-love-arch-but-gnu-guix-is-my-new-distro
https://boilingsteam.com/how-i-built-my-new-linux-gaming-desktop-in-2021-with-amd-cpugpu-and-gnu-guix/

Currently I am building my own Gaming Desktop using the old AMD Opteron. I recently added a 1TB SSD, installed Trisquel and found a water cooling that works with the G34 Socket. I'm also huge fan of GNU Guix, and used it on my Talos II before Trisquel got ported. But Trisquel is also great since it has packages that guix is missing and sometimes it is easier to use. The article talks about nonguix which I want to avoid, since all software in that repository is non-free and in many cases X86 only. I knew theoretically my Opteron System could run Steam and many of its nonfree DRM'd Games using Proton. Maybe I'll install Proton, but only to test Windows software that I have cross-compiled using MinGW.

It does not have an AMD GPU, because those need non-free firmware. Instead I use an old GeForce 9500 GT which as free firmware. This is not good enough for modern gaming, so I will focus on retro. I guess that many games such as SuperTux and Wesnoth will be even playable without the NVIDIA GPU, just using the ASPEED VGA and software rendering on the Opteron. But on the long term I plan to get Vulkan and Veloren running, using software rendering on the CPU while offloading some rendering stages to the NVIDIA GPU which unlike the Opteron as a Texture Mapping Unit. I also use it as build server for Android/Replicant.