Possible to use in sub layout or in the views about vaadin-app-layout

[appreciated]

Sorry but I'm not sure If I understand your question correctly, would you mind using sth. like paint to explain it to me? It does not need to look good. I just need to know what (and where) do you want the current behavoir to be different?

[appreciated]

With this method you can manipulate the Navigator View Holder (Where the Navigator puts the views)

withNavigatorProducer(componentHolder -> {
                    VerticalLayout leftContent = new VerticalLayout(new Button("My Button"));
                    VerticalLayout rightNavigatorContent = new VerticalLayout();
                    HorizontalLayout holder = new HorizontalLayout();
                    holder.setSizeFull();
                    componentHolder.addComponent(holder);
                    return new Navigator(this,rightNavigatorContent);
                })

[appreciated]

And you can try to wrap the layout inside of other Component

  HorizontalLayout layout = new HorizontalLayout(new Button(), drawer);
        layout.setSizeFull();
        setContent(layout);

But this requires some additional css manipulation since the Menu is position:fixed to the left.

SCSS

.left-navigation-drawer-responsive {
    overflow: hidden;
    app-drawer{
         position:absolute;
    }
   .drawer-content {
      box-shadow: none; 
      margin-top: 0px;
    }
}

If this is neither what you intend to do give me some input please.