Is there a way to make MacOS convert the mouse events to a touch events?

It is not a good idea to mess with the Qt event handling yourself. The reason why it does not seem to do touch events for you is because you have to explicitly enable this in your Qt application.

Please refer to the following page for details.

To receive touch events, widgets have to have the Qt::WA_AcceptTouchEvents attribute set and graphics items need to have the acceptTouchEvents attribute set to true.

And then, you can reimplement QObject::event(QEvent *e).

You can find the event types here where you will also find the touch event type to handle.

QEvent::TouchBegin Beginning of a sequence of touch-screen or track-pad events (QTouchEvent).

QEvent::TouchCancel Cancellation of touch-event sequence (QTouchEvent).

QEvent::TouchEnd End of touch-event sequence (QTouchEvent).

QEvent::TouchUpdate Touch-screen event (QTouchEvent).

So, to put it all into practice, you would write something like this:

MyWidget::MyWidget(QWidget *parent) : QWidget(parent)
{
   ...
   setAttribute(Qt::WA_AcceptTouchEvents);
   ...
}

or just this outside the class definition:

myWidget->setAttribute(Qt::WA_AcceptTouchEvents);

And then, you actually handle touch events:

bool MyWidget::event(QEvent* event)
{
    switch (event->type()) {
    case QEvent::TouchUpdate:
        // Handle
        break;
    default:
        break;
        
    }
    return QObject::event(event);
}