@Darya thank you for the discussion!
You can use the ApplicationShell#addWidget
to add your widget (button, icon, menu, etc.) to the topPanel
and style your element to the right with CSS.
Ex:
this.applicationShell.addWidget(widget, { area: 'top' });
Where to write this code
@tt2592 any use of the framework, additional implementations, customizations would need to be contributed in your own custom extension.