Yes however you’re conflating the names of both which is where the confusion lies.
Cosmic is a portion of Pop Shell, which is what you’re calling “Gnome-based Cosmic DE”. This collection of gnome extensions forms what is called Pop Shell. The cosmic here only refers to the extension that modifies the dock, workspace and configuration changes and is not a desktop environment.
Cosmic DE refers to the “rust based” full desktop environment called Cosmic DE which has nothing gnome within it.