> I mean a standard 64-bit open source motherboard, peripherals, etc that aren’t locked down with binary blobs.

The problem here is scale. Having fully-open hardware is neat, but then you end up with something like that Blackbird PowerPC thing which costs thousands of dollars to have the performance of a PC that costs hundreds of dollars. Which means that only purists buy it, which prevents economies of scale and prices out anyone who isn't rich.

Whereas what you actually need is for people to be able to run open code on obtainium hardware. This is why Linux won and proprietary Unix lost in servers.

That might be achievable at the low end with purpose-built open hardware, because then the hardware is simple and cheap and can reach scale because it's a good buy even for people who don't care if it's open or not.

But for the mid-range and high end, what we probably need is a project to pick whichever chip is the most popular and spend the resources to reverse engineer it so we can run open code on the hardware which is already in everybody's hands. Which makes it easier to do it again, because the second time it's not reverse engineering every component of the device, it's noticing that v4 is just v3 with a minor update or the third most popular device shares 80% of its hardware with the most popular device so adding it is only 20% as much work as the first one. Which is how Linux did it on servers and desktops.