This is a fork of "Poppy Menu" that I have modified adding some functions and decorations to make the menu more similar to the macOS menu in its Big Sur version and thus bring it to Gnome as an extension in the Shell.
There are two ways to install the extension on your distro with Gnome Desktop; the first is manually, the second, and easier, is the installation from the official page of Gnome Extensions
To do a manual installation, all you have to do is download the extension from Big Sur Menu for Gnome Desktop and unzip the file to obtain a folder that you must move to the path:
/.local/share/gnome-shell/extensions/
To see the /.local/ folder you need to access the hidden files and for that you must first press the "ctrl + h" keys or go to the Nautilus menu and check the Show Hidden Files box.
To install from the Gnome Extensions page, go to the following link: Big Sur Menu for Gnome Desktop and turn on the extension, then confirm the installation and voila, you already have the macOS Big Sur style menu in Gnome Desktop.