Just FYI, the info-look module can be configured to also look up things in the
elisp manual. I've been using it to do this for years now, via
`info-lookup-symbol'. And it's already part of Emacs, so we'd just need to
integrate by default.
It does look up symbols under elisp manual from time to time. The problem here is for functions like `delete-char', both emacs manual and elisp manual contain it and info-lookup-symbol prefers the latter under both emacs-lisp-mode and lisp-mode.
Possible to tell info-lookup-symbol prefer elisp manual ?