WebAssembly doesn't make native integration any easier than JS. Neither defines the exact way so called non-web embeddings actually are defined and both can support it. I honestly have no idea the relevance of WebAssembly in this discussion. Could you provide an illustrative example?
Edit: I should clarify that for certain types of apps WebAssembly might be relevant but the discussion seemed to be out UI layer and I don't understand how WebAssembly fills a gap that a native API in JS could also provide along with the same challenges.
Edit: I should clarify that for certain types of apps WebAssembly might be relevant but the discussion seemed to be out UI layer and I don't understand how WebAssembly fills a gap that a native API in JS could also provide along with the same challenges.