The reason I ask is that I was poking around and saw some projects to help with wasm compilation, and on this random list of wasm-capable languages [0], Nim is listed as "Work in Progress." Notably, Swift is ranked higher, and I view Swift as extremely experimental when it comes to wasm
With 2.0 out and ORC being default it compiles and works just fine. There's not too many libraries specializing for wasm stuff though, so you gotta use emscriptens or similar.
[0]: https://github.com/appcypher/awesome-wasm-langs