Accessing TableView from second QML file with PySide2

I am having two different QML files. In the main.qml I am using a Loader to call another QML file (other.qml). The second file contains a TableView which I want to access with Python ( by creating a class implementing QtCore.QAbstractTableModel. Unfortunately, I am not able to access activityTable with Python when loading the main.qml in Already, the assignment of the model in main.qml fails.
How do I make this TableView accessable in Python?


TableView {
    id: activityTable
    anchors.fill: parent
    columnSpacing: 1
    rowSpacing: 1
    clip: true

    model: ActivityTableModel {}

    delegate: Rectangle {
        implicitWidth: 100
        implicitHeight: 50
        Text {
            text: display


Loader {
    id: pagesOther
    anchors.fill: parent
    source: Qt.resolvedUrl("pages/other.qml")

if __name__ == "__main__":
    app = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()

    main = MainWindow()
    engine.rootContext().setContextProperty("backend", main)
    engine.load(os.path.join(os.path.dirname(__file__), "qml/main.qml"))

I am using QtCreator, QtQuick 2.15, PySide2 and Python 3.9.