I'm trying to find where the contents of the *GNU Emacs* buffer, aka fancy startup screen, are located on my hard drive.
M-x eval-expression buffer-file-name to find the file of the current buffer it returns nil. It says in the docs for buffer-file-name:
If buffer is not visiting any file, buffer-file-name returns nil.
so this is expected.
If it is not a file then where is this text coming from? I checked the source code at https://github.com/emacs-mirror/emacs/tree/master/doc but I didn't see anything.