from PySide6.QtWidgets import QApplication, QWidget, QMainWindow, QPushButton
import sys

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.is_checked = True

        self.setWindowTitle('my App')
        self.setMinimumSize(400,300)

        button=QPushButton('Press me')
        button.setCheckable(True)
        button.clicked.connect(self.toggled)
        button.setChecked(self.is_checked)

        self.setCentralWidget(button)


    def toggled(self, checked):
        self.is_checked = checked

        print(self.is_checked)

app = QApplication(sys.argv)

window = MainWindow()
window.show()

app.exec()