Well the great thing about WebAssembly is that you can port QT or anything else to be at a layer below -- thanks to WebAssembly Interface Types[0] and the Component Model specification that works underneath that.
To over-simplify, the Component Model manages language interop, and WIT constrains the boundaries with interfaces.
IMO the problem here is defining a 90% solution for most window, tab, button, etc management, then building embeddings in QT, Flutter/Skia, and other lower level engines. Getting a good cross-platform way of doing data passing, triggering re-renders, serializing window state is probably the meat of the interesting work.
On top of that, you really need great UX. This is normally where projects fall short -- why should I use this solution instead of something like Tauri[2] which is excellent or Electron?
