@ryo More about that motherboard later, but first, the point about Nvidia:
I know about the drivers. I'm saying that you can't run AMD GPUs on Librebooted hardware, because they require proprietary firmware, which is where they get you. That's why you can't use the AMD GPUs in Librebooted ThinkPads. But apparently, you can use Nvidia, presumably with Nouveau. So if you want to go 100% free but still have a more recent GPU, you have to use Nvidia. Unless I'm getting this wrong, this is all from random things I read (I think in threads about people trying to get GPUs working on the ThinkPad Advanced Dock's PCIe port.
I want to test this myself eventually, on one of those cheap motherboards, but haven't yet. But if it's true, Nvidia is more free software-friendly than AMD, despite trying their hardest to be worse. So, AMD is known as the supposedly free software-friendly corporation (which they're not, again, they require proprietary firmware, and they repeatedly refused to open source the PSP, because they are hiding a bunch of spyware in there and they don't want you to know, they are no better than Intel, they are like the Donald Trump of CPUs), but the free x86 systems almost all have Intel CPUs (there are those AMD server boards, but I don't remember anything else), and the only GPUs that work are Nvidia's.
So, AMD will pretend to be your friend if you want to go 99% free, but if you want to go 100%, you have to go Nvidia, and deal with the free drivers, but at least it's possible.
Anyway, the actual motherboard is this:
https://libreboot.org/docs/hardware/ga-g41m-es2l.htmlI think it MIGHT work. Seems like you don't have video initialization on the more recent version of Libreboot, but you don't need it if you use a GPU. On the other hand, video initialization works with an older version, but then PCIe doesn't work. Worth a try, maybe. Maybe there's more information out there. It's cheap, though. Just don't tell JewToobers about it or the price will go up by 10 times.