I'm not going to port to tkinter. I like KDE, I like Qt Designer, and I have a working GUI. If tkinter is the only thing that works in Python I'll abandon the language (I mostly work in Scala these days anyway) and find one with working Qt bindings.
I like catching errors at compile time. But C++'s unchecked manual memory management introduces more errors than the rest of the language eliminates, undefined behaviour turns all bugs into security bugs, there aren't first-class sum types (std::variant is finally on the way in but seems quite restricted; std::visit, while much better than what came before, is pretty cumbersome), and templates are cumbersome in syntax (and error reporting) and not as safe as they look thanks to partial specialization (which will be fixed by concepts if they ever actually make it into the language, but, well...). Along with plenty of less immediate problems (e.g. the lack of a module system).
If there were an ML-family language with good Qt support I'd use that for my GUIs - I use ML-based languages for almost all my non-GUI work. There's plenty I dislike about Python but it's still the best desktop GUI experience I've found.
A project you might be interested in is libui (https://github.com/andlabs/libui). I can't comment on it because I haven't used it and it's still quite young but it looks promising, it's on my radar to learn soon. Native widgets and written in c so the bindings should be stable. I've never written bindings for c++ but I'm guessing it's not easy because all the c++ toolkit bindings are unstable.
