Maybe they've improved, but banana pi/sinovoip used to ship images based on android kernels.

Rockchip have a reputation of fully working with the open source community, though I can't personally say how well. Most other SoC vendors only do enough to get android going.

Given that Android is basically the most popular "distro" of ARM Linux, that's not surprising.

However, I was referring to the availability of documentation which for these Chinese SoCs is either officially released or soon leaked.

Leaked SoC documentation is a very long distance from having a fully working open ecosystem. Like, dozens of man-years -maybe hundreds. It would be a mistake to assume you can pick any of the sinovoip boards and get that. They use a number of SoC vendors with very different business models, and level of support for FOSS. Certainly there are some who make much less investment in maintaining an open ecosystem than RPI.

x86 PCs need insecure and ordinarily impossible to replace blobs in order to boot. It's true that PC firmware doesn't seem to hurt open source people's feelings quite so much as it once did, but there's not a ton of logic to that.

Coreboot has been around for over a decade.

I'm not taking the "security" bait at all, especially when we're comparing a PC to an even less-explored platform which also requires binary blobs.

Unless things have changed significantly coreboot is an example of what I'm talking about - not a ton of x86 motherboard hardware is supported very well. "But for real openness, nothing beats an older x86 PC" just doesn't seem true at all.

(but I'll look into coreboot. I'd get a kick out of trying it.)