Application running with eglfs or vkkhrdisplay QPA does not create pipeline cache file when stopped. Only when running app with window manager (x11, wayland) and terminating it via window manager "X" button from application window will cause pipeline cache file to be created. Documentation does not state that pipeline cache would not be supported with those QPA platforms. So the "automatic" (https://doc.qt.io/qt-6/qquickgraphicsconfiguration.html#the-automatic-pipeline-cache) pipeline cache feature is missing.

Currently in order get pipeline cache created when application exits/terminates one needs to manually call:

            window->hide();
            window->releaseResources();

And connect to QQuickWindow::sceneGraphAboutToStop signal in which application needs to exit using  QCoreApplication::exit() function.