Most interfaces created through web technology would be incredibly hard and slow to do using pyside/pyqt. We take for granted the non-blocking aspect of javasript where in python in order to make a slick interface would require to deal with threads/GIL in a much slower interpreted language compared with javascript running on V8.

Qt (Qt Desktop) bindings for python are welcome. But, it's not a suitable for a viable replacement for electron. Maybe Qt Quick, but even qt quick has some decisions that can make incredibly uncomfortable to use in large applications.