There is emscripten-qt that built Qt apps w/ Emscripten for a while now[0] (since asm.js and WASM should not change anything even though it hasn't had updates in a few years). Appears this uses Emscripten as well. I wonder how this compares at a tech level.
It's impressive and exciting it can run a full app like KATE. It feels as if you're running a Linux VM inside the browser, but no!