Python and PyQT6 / QFileDialog: Cannot get the list of filenames

Question

I think I understand Python classes, but obviously I do not (Newbie in Python).

I have a class MainWindow(QWidget) and I want to use the outcome if the file selection dialog in the main program or somewhere else. That means, I want to get (export) the variable filenames in open_file_dialog(self)-

Maybe the code example shows my problem more clearly.

import sys
from PyQt6.QtWidgets import (
    QApplication, 
    QWidget, 
    QFileDialog, 
    QGridLayout,
    QPushButton, 
    QLabel,
    QListWidget
     
)
from pathlib import Path


class MainWindow(QWidget):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.setWindowTitle('PyQt File Dialog')
        self.setGeometry(100, 100, 300, 150)

        layout = QGridLayout()
        self.setLayout(layout)

        # file selection
        file_browser_btn = QPushButton('Browse')
        file_browser_btn.clicked.connect(self.open_file_dialog)

        self.file_list = QListWidget(self)

        layout.addWidget(QLabel('Files:'), 0, 0)
        layout.addWidget(self.file_list, 1, 0)
        layout.addWidget(file_browser_btn, 2 ,0)

        self.show()

    def open_file_dialog(self):
        dialog = QFileDialog(self)
        dialog.setDirectory(r'C:')
        dialog.setFileMode(QFileDialog.FileMode.ExistingFiles)
        dialog.setNameFilter("Text (*.txt *.eml)")
        dialog.setViewMode(QFileDialog.ViewMode.List)
        if dialog.exec():

            self.lw = QWidget.QListWidget()

            filenames = dialog.selectedFiles()
            if filenames:
                self.file_list.addItems([str(Path(filename)) for filename in filenames])
                # y=self.file_list
                # super().y=self.file_list
                # MainWindow.y=self.file_list
                # MainWindow.y=filenames
                QWidget.QListWidgetItem('myItem only 1', self.lw)
                
    x=1
    # y=self.file_list
    # y=filenames



if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    # fnames = QStringList()
    # print (window.__getattribute__ ('file_list'))
    # print (window::file_list())
    # print (window.dialog.selectedfiles ())
    # print (window.selectedfiles())
    # print (window.filenames)
    # print (window.file_list [1])
    # print (window.y [1])
    # print (window.y)

    # lst = QWidget.file_list()
    # lst = QWidget.lw()
    # lst = QWidget.QListWidget()
    lst = window.QListWidget()
    items = []
    for x in range(lst.count()):
        items.append(lst.item(x).text())
    print(items) 
   
# I want the list of selected files here, nothng works ...

    sys.exit(app.exec())