Anyway, this is really a matter of implementation, not a language issue. There's nothing about Zig that makes it inherently impossible to support SH2 or any other platform - indeed, as others have noted, they already have a C backend in the works, so the endgame is to support everything that has a C compiler.
Also, as far as C interop goes, if I remember correctly, Nim can't just take a C header and expose everything declared in it - you still have to manually redeclare the functions and types that you want in Nim, no? You can use c2nim, of course, but that's not really any different than generators for other languages, and requires extra build steps etc. Zig handles it all transparently.
I think separating the two is a bit artificial. Python being slow is partially an implementation issue but the fast implementations can't run everything. When you compare languages, you have to compare implementations, otherwise it's meaningless.
That's kind of what people are getting at in this whole conversation though isn't it, ecosystems around languages matter. They can't be an afterthought.
I'm not even sure why arch support was brought up in this thread, to be honest, because it's not relevant at all? If your problem is unsupported architecture, it's a blocker long before you need to use any libraries...
