> The answer was as unhelpful as possible

Looking at the answer, I wouldn't call it unhelpful. They were planning to release a source for the library that would essentially implement all the needed data interfaces? That's more than helpful and at least they responded.

I tried contacting Nuvoton for example about their documentation for some of their super I/O chips which lack Linux support (they do document a bunch of their chips pretty well, but for some weird reason not all).

Not only I got no details, I literally didn't even get a response from them at all. So above case is hugely better.