Even more honest would be “on one particular microbenchmark that everybody optimizes for”.
That said, this seems like a really cool project that could have some real value! It still fully depends on having the full CPython runtime environment, but that means it could work correctly with most existing code and libraries (including numpy and script).
From what I could tell, Nuitka dynamically loads extension modules so this wouldn't work with Webassembly modules which are statically linked. If I could be enhanced to automatically build wheels of packages like numpy and statically link them, then that could bring extensions to Wasm and be very cool. IIRC, Google does this with their Python apps so the concept does exist but don't think I've seen any OSS tooling trying that.
That said, this seems like a really cool project that could have some real value! It still fully depends on having the full CPython runtime environment, but that means it could work correctly with most existing code and libraries (including numpy and script).