They are now investing into Python as official supported language.
Well, it was about time. Pyside is a quite old project that for a while almost seemed to have fallen into oblivion. Glad to see that they are finally using it as official binding tool.
WxWidgets is now available & stable(!) for Py3 and available on PyPI for easy installation & distribution. Moreso, the dev pipeline has been streamlined and they are now able to follow upstream much more closely! Maybe this is sth for you.
Nevertheless I'm surprised to read you had to compile anything (if you don't mean using pyuic5 to generate Python classes from QtDesigner XML files) and deal with C++ while using Qt5 with Python.