Showing Scene3D in Qt Quick Item

I try to show a Scene3d in a Qt Quick so that it just fits into this Item, considering the aspect ratio of the scene. The scene is loaded with Qt Quick's SceneLoader.

I experimented with aspect ratio, width, implicitHeight in Camera, Entities and so on.

But I do not succeed. The scene is principally depicted but with wrong scaling.

Does anybody know how could it be solved? Thank you.

My current solution approach is like this snippet:

Item {
    id: item
    Layout.fillWidth: true
    Layout.fillHeight: true
    Scene3D {
        id: scene
        width: height / myObject.aspectRatio
        anchors.top: item.top
        anchors.bottom: item.bottom
        aspects: ["input", "logic", "render"]
        cameraAspectRatioMode: Scene3D.UserAspectRatio
        Entity {
            id: mainEntity
            components: [
                RenderSettings {
                    activeFrameGraph: ForwardRenderer
                    {
                        clearColor: Qt.rgba(0, 0.5, 1, 1)
                        camera: camera
                    }
                },
            ]
            Camera {
                id: camera
                projectionType: CameraLens.OrthographicProjection
                aspectRatio: myObject.aspectRatio
                position: Qt.vector3d(0.0, 0.0, 5.0)
                viewCenter: Qt.vector3d(0.0, 0.0, 0.0)
            }
            Entity {
                id: myObject
                property real aspectRatio: 1.0
                components: [
                    SceneLoader {
                        id: sceneLoader
                        source: "file:///xxx/myObject.obj"
                        onStatusChanged: {
                            if (status === SceneLoader.Ready) {
                                myObject.aspectRatio = computeAspectRatio();
                            }
                        }
                    }
                ]
                function computeAspectRatio() {
                    ...
                }
            }
        }
    }
}