there are soqt libraries available which build with qt5. Pivy needs a soqt-config, which isn't generated with cmake.
the bitbucket soqt version has some problems with cmake. My older version works with cond (linux) https://github.com/looooo/soqt. Find the relevant stuff and make PR for soqt
pivy needs to be updated to pyside2. It's allready possible to build the library, but soqt/quarter won't work yet. Quarter should be simple as it's all on python level. SoQT is hopefully also not to hard to port, as the used PySide stuff is not very much.