In Info-mode, "G" is bound to Info-goto-node-web which opens the 
current manual-node in the browser. It uses `Info-url-for-node' to 
determine the URL, which only supports "elisp" and "emacs" 
manuals.

Are you interested in a patch that adds support for more manuals? We could extend supported docs to include one of these nested sets of software packages:

(1.) All manuals that Emacs contains. I.e. these?: auth autotype 
bovine calc ccmode cl dbus dired-x ebrowse ede ediff edt eieio 
elisp emacs-gnutls emacs emacs-mime epa erc ert eshell eudc eww 
flymake forms gawk gnus htmlfontify idlwave ido info mairix-el 
message mh-e newsticker nxml-mode octave-mode org pcl-cvs pgg 
rcirc reftex remember sasl sc semantic ses sieve smtpmail speedbar 
srecode todo-mode tramp url vhdl-mode viper vip widget wisent 
woman.

(2.) Some more or all manuals on gnu.org.

(3.) Some more or all manuals of the GNU project, including those with external websites (or subdomains of gnu.org), e.g. gcc.gnu.org, guix.gnu.org, magit.vc, octave.org.

(4.) Some more manuals of free software with docs generated with "makeinfo".

Yesterday, I wrote a solution for (3.) in my personal Emacs configuration, using an advice for Info-url-for-node. It's attached inline: