I think WASM is ready for production use. Emscripten does produce big blobs of JavaScript. If it bothers you it's possible to do WASM without Emscripten. If your embedded code doesn't use a lot of libc then it might actually work for you. https://surma.dev/things/c-to-webassembly/
The big gotcha used to be debugging but Chrome dev tools actually has DWARF support now. Of course as an embedded developer you're probably already used to poor debugging support.
Heavy use of libc for file io and dynamic memory allocation, but not much else. Some of our code could be converted to using static memory buffers, but we also use some third party libraries that are not so easily changed. Thanks for the link, I will have a look!
The big gotcha used to be debugging but Chrome dev tools actually has DWARF support now. Of course as an embedded developer you're probably already used to poor debugging support.