Some time ago I wanted to make a cross-platform app in python, I wanted to use the ui bindings of each platform, I had some success with Cocoa in OSX but when I tried in windows, I saw with IronPython I could use WPF but when I tried to use it, it was reaally outdated and there wasn't even IronPython for python3... I guess it is no longer in active development... In the end I used swift in osx and c# windows, but I would have loved to use .net apis in python and have the same codebase for all the platforms.