JVM requires almost all your stack to be rewritten for it.
Because WebAssembly permits languages to be usable in the web, almost any other language (C, C++, Rust, Go and even Java) is now working to be compiled to WebAssembly.
Therefore you don’t need to adapt your stack to run it in Wasmer :)
Although your point is completely right, once your application is in wasm perhaps you can use directly a wasm vm (wasmer) instead of another transpiler and the jvm :)
Because WebAssembly permits languages to be usable in the web, almost any other language (C, C++, Rust, Go and even Java) is now working to be compiled to WebAssembly.
Therefore you don’t need to adapt your stack to run it in Wasmer :)