PySide6 provides Qt Python bindings. The version of PySide6 used with Maya can be found on the Open Source Components page.
Some things to keep in mind when working with PySide6 are:
A unique objectName() is needed for your widget so that it can be used and looked up through maya.OpenMayaUI.MQtUtil.findControl().
There are no native sizing preferences for PySide6 widgets. You can use the windowPref command directly to set the sizing preferences.
When docking windows, the size of the widget is retained and you can dock multiple windows to the same area so that you can switch among them via a tab as with Maya.
You must parent your widget under an existing Maya widget to prevent it from being destroyed by the Python garbage collector. You can parent the widget to the Maya main window or the dock control. For example:
from PySide6.QtCore import Qt
from PySide6.QtWidgets import QMainWindow, QLabel
from maya import OpenMayaUI as omui
from shiboken6 import wrapInstance
mw_ptr = omui.MQtUtil.mainWindow()
mayaMainWindow = wrapInstance(int(mw_ptr), QMainWindow)
hello = QLabel("Hello, World", parent=mayaMainWindow)
hello.setObjectName('MyLabel')
hello.setWindowFlags(Qt.Window) # Make this widget a parented standalone window
hello.show()
hello = None # widget is parented, so it will not be destroyed.Several example PySide6 scripts are provided in the Maya devkit in pythonScripts under the devkit directory.