The QML bindings for other languages don't have to cover much surface area though. They look minimal but most of them are eminently usable because all the UI logic is in the QML+JS, all you need in a binding is a way to pass data in and out.
D, Rust, Go, Ruby, Python, etc... all have good enough bindings, that work for now and even if they do need some patching, aren't that big or hard to patch yourself. I've never used them myself (I just use C++, but I plan on using D for a QML app someday), but I know some other projects that do like https://github.com/limetext/lime
Something to do while snowed in.
The only really complete bindings for Qt 5 are PyQt5 but its not compiled so its out for me. There are solid qml bindings for go and the rust ones worked fine last time I tested. Im not really a big fan of QML though. Its really much different than using widgets and Im not a Javascript dev by any means.
The QML side of things I've never tried, and the QML based bindings to other languages in general seem less mature than the C/C++ bindings. I'm keeping an eye on go-qml though.
I wonder if PyQt works with Cython. That could be interesting.
Because it looks abandoned nowadays, I've tried pyinstaller recently. It worked OK, too; the only thing that was slightly annoying was pulling in the Windows 8/2012 (api-ms-win-*) style system dlls.
For example, if I had anything that used numpy (which is most of my code) or Qt, or a lib that uses opengl, it would either fail outright saying "can't find blarg" or it would spin forever. Now I understand that the process of transpiling something huge like numpy and then compiling it will be fairly demanding, but I've literally left this stuff running in a tmux session for a day or two and it showed now sign of ever finishing.
I'm not asking you to debug my stuff or anything, but have you had a different experience? Is there a trick to getting Nuitka to build code that leverages the python ecosystem? I would really like to figure this out, because the alternatives are really quite terrible, IMO. If Nuitka can be made to work with build times less that a week, I think he's really on to something.