Actually your question made me look for the language binding pages of Qt and Gtk... I was going to say that alternative language support was much better in Gtk thanks to it having a C API as opposed to Qt with a C++ API (because C is much easier to interface with from other languages)

But now that I see it, seems that Qt has a quite interesting list of language bindings!

Qt: https://wiki.qt.io/Language_Bindings

Gtk: https://www.gtk.org/docs/language-bindings/index