PySimpleGUIQt does not import inside QGIS, DLL not found

Question

I am trying to run a script inside QGIS that uses pySimpleGUIQt. I can't get it to work, a DLL is not found.

Configuration

Win10 64b, QGIS 3.16 (Python 3.7)

Steps to reproduce the error

• Open osgeo4w shell, type py3_env to setup the python environment
• Type python -m pip install PySimpleGUIQt
• Launch QGIS and open Python console, type import PySimpleGUIQt

Error thrown

import PySimpleGUIQt as sg
  File "MY_PERSONNAL_PATH_TO_PYTHON37\site-packages\shiboken2\files.dir\shibokensupport\__feature__.py", line 142, in _import
    return original_import(name, *args, **kwargs)
  File "C:/PROGRA~1/QGIS3~1.16/apps/qgis-ltr/./python\qgis\utils.py", line 792, in _import
    mod = _builtin_import(name, globals, locals, fromlist, level)
  File "MY_PERSONNAL_PATH_TO_PYTHON37\site-packages\PySimpleGUIQt\__init__.py", line 2, in 
    from .PySimpleGUIQt import *
  File "MY_PERSONNAL_PATH_TO_PYTHON37\site-packages\shiboken2\files.dir\shibokensupport\__feature__.py", line 142, in _import
    return original_import(name, *args, **kwargs)
  File "C:/PROGRA~1/QGIS3~1.16/apps/qgis-ltr/./python\qgis\utils.py", line 792, in _import
    mod = _builtin_import(name, globals, locals, fromlist, level)
  File "MY_PERSONNAL_PATH_TO_PYTHON37\site-packages\PySimpleGUIQt\PySimpleGUIQt.py", line 25, in 
    from PySide2.QtWidgets import QApplication, QLabel, QWidget, QLineEdit, QComboBox, QFormLayout, QVBoxLayout, QHBoxLayout, QListWidget, QDial, QTableWidget
  File "MY_PERSONNAL_PATH_TO_PYTHON37\site-packages\shiboken2\files.dir\shibokensupport\__feature__.py", line 142, in _import
    return original_import(name, *args, **kwargs)
  File "C:/PROGRA~1/QGIS3~1.16/apps/qgis-ltr/./python\qgis\utils.py", line 792, in _import
    mod = _builtin_import(name, globals, locals, fromlist, level)
ImportError: DLL load failed: La procédure spécifiée est introuvable.

Answer 1

I posted the issue on the QGIS github : https://github.com/qgis/QGIS/issues/45960 I had a clear answer from the devs : this is not supported. You have to work with Qt and Qt designer inside Qgis and not other Qt-based python libraries.