$ mkdir test
$ python3 -m venv venv
$ source venv/bin/activate
$ pip install PySide2
$ cat << EOF > main.py
import sys

from PySide2.QtWidgets import QApplication, QLabel
                                                     
if __name__ == '__main__':
    app = QApplication([])
    label = QLabel("Hello World")
    label.show()
    sys.exit(app.exec_())
EOF
$ python main.py