Yes it can! Wasm3 is the fastest WebAssembly interpreter. Since they recently adopted Cosmopolitan it became the most universal one too. Check out the 150kb APE binary they've got on the release page. https://github.com/wasm3/wasm3/releases/tag/v0.4.8

Depends on what you mean by “using”. It is conceivably possible to compile a webassembly interpreter like wac[1] with cosmopolitan, which would then run on all OSes and bare metal, yes.

[1]: https://github.com/kanaka/wac

That's not as portable as you need an interpreter.