@BenM pointed out that he had problems compiling the qt bindings for MacOS. Please add some errors you see here.
It was additionally pointed out to me today that the find script for Qt does not work well on MacOS in the absence of pkgconfig files. KDE's craft uses this hackery: https://github.com/KDE/craft-blueprints-kde/blob/master/libs/_autotools/gpgme/gpgme.py#L34
I should probably look into this :-/