QDesktopServices is unable to open a file on Android

#include <QApplication>
#include "mainwindow.h"
int main( int argc, char* argv[] )
{
    QApplication app(argc, argv);
    MainFrame frame;
    frame.show();
    return app.exec();
}

#pragma once
#include <QMainWindow>
class MainFrame : public QMainWindow
{
    Q_OBJECT
public:
    MainFrame();
public slots:
    void openFromQt();
    void openFromSDK();
private:
    void fixOpenFile();
    std::string fileName;
};

#include "mainwindow.h"
#include <QVBoxLayout>
#include <QPushButton>
#include <QFile>
#include <QMessageBox>
#include "qandroidextras_p.h"
#define QtAndroid QtAndroidPrivate
#define requestPermissionsSync requestPermissions
#include <QJniObject>
#include <QJniEnvironment>
#include <QDesktopServices>
#include <QUrl>
#include <QDebug>
#include <QStandardPaths>
#include <string>
#include <fstream>
MainFrame::MainFrame()
{
    // bug reported for Qt 6.2.2 here: https://bugreports.qt.io/browse/QTBUG-47979
    // workarounded by https://bugreports.qt.io/browse/QTBUG-67877
    // new bug reported for Qt 6.9.0
    fileName = (QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation) + "/" + CURRENT_MODULE_NAME + ".txt").toStdString();
    
    auto result1 = QtAndroid::requestPermission("android.permission.WRITE_EXTERNAL_STORAGE");
    result1.waitForFinished();
    if ( result1.result() != QtAndroid::PermissionResult::Authorized )
    {
        qCritical() << "Failed to get privileges for writting";
    }
    auto result2 = QtAndroid::requestPermission("android.permission.READ_EXTERNAL_STORAGE");
    result2.waitForFinished();
    if ( result2.result() != QtAndroid::PermissionResult::Authorized )
    {
        qCritical() << "Failed to get privileges for writting";
    }
    // create a file:
    std::fstream file;
    file.open( fileName.c_str(), std::ios_base::out );
    file << "Hello World!" << std::endl;
    file.close();
    if (QFile(fileName.c_str()).exists())
        QMessageBox::information(NULL,"","File exists");
    else
        QMessageBox::information(NULL,"","File does not exist");
    QWidget* centralWidget = new QWidget( this );
    centralWidget->setLayout( new QVBoxLayout() );
    QPushButton* qt_button = new QPushButton( "Open with Qt", centralWidget );
    QObject::connect( qt_button, SIGNAL(clicked()), this, SLOT(openFromQt()) );
    centralWidget->layout()->addWidget( qt_button );
    QPushButton* sdk_button = new QPushButton( "Open with SDK", centralWidget );
    QObject::connect( sdk_button, SIGNAL(clicked()), this, SLOT(openFromSDK()) );
    centralWidget->layout()->addWidget( sdk_button );
    setCentralWidget( centralWidget );
}
void MainFrame::fixOpenFile()
{
    // see https://bugreports.qt.io/browse/QTBUG-67877
    QAndroidJniObject DisableDeathOnFileUriExposureObject("my/common/DisableDeathOnFileUriExposureHelper","()V");
    if ( DisableDeathOnFileUriExposureObject.isValid() )
    {
        jboolean worked = DisableDeathOnFileUriExposureObject.callMethod<jboolean>("doDisableDeathOnFileUriExposure","()Z");
        if ( worked )
            qDebug() << "OK";
        else
            qDebug() << "KO";
    }
    else
    {
        assert( false );
    }
}
void MainFrame::openFromQt()
{
    fixOpenFile();
    // use Qt code to open a file. Works on PC, not on Android
    QUrl url = QUrl::fromLocalFile(fileName.c_str());
    QDesktopServices::openUrl(url);
}
std::string GetFileType( const std::string& fileName )
{
    QAndroidJniObject javaFileName = QAndroidJniObject::fromString(fileName.c_str());    //type is valid
    QAndroidJniObject extension = QAndroidJniObject::callStaticObjectMethod("android/webkit/MimeTypeMap",
                                                                            "getFileExtensionFromUrl",
                                                                            "(Ljava/lang/String;)Ljava/lang/String;",
                                                                            javaFileName.object<jobject>());
    if ( extension.isValid() )
    {
        std::string ext = extension.toString().toStdString();
        QAndroidJniObject mime = QAndroidJniObject::callStaticObjectMethod("android/webkit/MimeTypeMap",
                                                                           "getSingleton",
                                                                           "()Landroid/webkit/MimeTypeMap;");
        if ( mime.isValid() )
        {
            QAndroidJniObject type = mime.callObjectMethod("getMimeTypeFromExtension",
                                                           "(Ljava/lang/String;)Ljava/lang/String;",
                                                           extension.object<jobject>() );
            if ( type.isValid() )
            {
                return type.toString().toSDEString();
            }
        }
    }
    return "text/plain";
}
bool startIntentToOpenFile( QAndroidJniObject& activity, const std::string& fileName, bool separatApp )
{
    bool opened = false;
    if ( activity.isValid() )
    {
        QAndroidJniObject intent("android/content/Intent","()V");
        if ( intent.isValid() )
        {
            QAndroidJniObject name = QAndroidJniObject::fromString(fileName.c_str());    //type is valid
            std::string mimeType = GetFileType(fileName);
            QAndroidJniObject type = QAndroidJniObject::fromString(mimeType.c_str());    //type is valid
            // should we actually use QAndroidJniObject::getStaticObjectField<jstring>("android/intent/action","ACTION_VIEW"); ?
            QAndroidJniObject action = QAndroidJniObject::fromString("android.intent.action.VIEW");
            if ( type.isValid() && name.isValid() && action.isValid() )
            {
                QAndroidJniObject file( "java/io/File","(Ljava/lang/String;)V",name.object<jobject>());
                if ( file.isValid() )
                {
                    jboolean exists = file.callMethod<jboolean>("exists","()Z");
                    if ( exists )
                    {
                        QAndroidJniObject uri = QAndroidJniObject::callStaticObjectMethod("android/net/Uri", "fromFile", "(Ljava/io/File;)Landroid/net/Uri;", file.object<jobject>());
                        if ( uri.isValid() )
                        {
                            //QAndroidJniObject string = uri.callObjectMethod("toString","()Ljava/lang/String;");
                            //const char *str1 = string.toString().toStdString().c_str();
                            intent.callObjectMethod("setDataAndType","(Landroid/net/Uri;Ljava/lang/String;)Landroid/content/Intent;",uri.object<jobject>(),type.object<jobject>());
                            intent.callObjectMethod("setAction","(Ljava/lang/String;)Landroid/content/Intent;",action.object<jobject>());
                            if ( separatApp )
                                intent.callObjectMethod("setFlags","(I)Landroid/content/Intent;",0x10000000);
                            if ( intent.isValid() )
                            {
                                //activity.callObjectMethod("startActivity","(Landroid/content/Intent;)V",intent.object<jobject>());
                                // recommended by https://bugreports.qt-project.org/browse/QTBUG-41395
                                activity.callMethod<void>("startActivity","(Landroid/content/Intent;)V",intent.object<jobject>());
                                opened = true;
                            }
                        }
                    }
                }
            }
        }
    }
    return opened;
}
void MainFrame::openFromSDK()
{
    fixOpenFile();
    auto activity = QJniObject(QNativeInterface::QAndroidApplication::context());
    startIntentToOpenFile( activity, fileName, false );
}

package my.common;
import java.lang.reflect.*;
import android.os.StrictMode;
public class DisableDeathOnFileUriExposureHelper
{
    public boolean doDisableDeathOnFileUriExposure()
    {
        try{
           Method m = StrictMode.class.getMethod("disableDeathOnFileUriExposure");
           m.invoke(null);
           return true;
        }catch(Exception e){
           e.printStackTrace();
           return false;
        }
    }
}