Hello, seem it's been a year since PyQt5 is supported in the gnuradio tree. QT5 is much easier to support on aarch64 and will allow gnuradio to run on that arch.
Stable is QT4 only https://github.com/gnuradio/gnuradio/blob/master/gr-qtgui/CMakeLists.txt#L25 It really doesn't matter what the development branch is using, we won't be switching until release from that is impending (which could be years)
