Pretty much, yes.
Getting in to the nitty-gritty a bit more, the app uses and angular component to display the page for your plugin, and the 'javascript' string returned is executed in the scope of that component. So if the javascript defines a method or property of this, the method or property is then part of that component, and available to be referenced from the template. If it has contains other arbitrary code, that will be executed within the scope of the component when it is loaded.