В wiki про WebAssembly вот такой бред написан в разделе Support:
Its initial aim is to support compilation from C and C++,[39] though support for other source languages such as Rust and .NET languages is also emerging.[40][41][36] After the MVP release, there are plans to support multithreading and garbage collection[42][43] which would make WebAssembly a compilation target for garbage-collected programming languages like C# (supported via Blazor), F# (supported via Bolero[44] with help of Blazor), Python, and even JavaScript where the browser's Just-in-time compilation speed is considered too slow. A number of other languages have some support including Java, Julia,[45][46][47] Ruby,[48] as well as Go.
Опустим то , что .NET, C#, F# и дважды упоминается Blazor. Проблема в прежде всего в том, что можно сделать вывод будто после GC пропозала можно будет компилировать JavaScript, Ruby и Python в WebAssembly. А сам JS слишком медленный