How to add custom menu in Photoshop?

Hello,

Is it possible to add a custom menu in Photoshop?

I'm using the following code as a startup script in InDesign, but it doesn't work for Photoshop:

(function(){
     alert("Hello world 1");
     var sma = app.scriptMenuActions.add("Create Photobook");
       
     // Add an Event Listener
     sma.addEventListener("onInvoke", function(){main()},false);
          
     // Create a new menu item in the Help submenu
     var mnu = app.menus.item("$ID/Main").submenus.item("$ID/&Help");
     mnu.menuSeparators.add();
     mnu.menuItems.add(sma);
})()
function main(){
     alert("Hello world 2");
}

In InDesign, this shows the following, and "Hello world 2" is displayed when selected:

In Photoshop, "Hello world 1" displays as soon as Photoshop is launched (as expected), but the "Create Photobook" menu is missing. No error is thrown.

Thanks!