Indeed, if you build the Lucid version you get a much smaller Emacs.
We had discussed this some time ago.

Here is a recipe:

--8<---------------cut here---------------start------------->8---
(define-public emacs-lucid
  (package
    (inherit emacs)
    (name "emacs-lucid")
    (synopsis "The Emacs text editor with Lucid support")
    (build-system gnu-build-system)
    (arguments
     (substitute-keyword-arguments (package-arguments emacs)
       ((#:configure-flags flags ''())
        `(cons "--with-x-toolkit=lucid" ,flags))
       ((#:phases phases)
        `(modify-phases ,phases
           (delete 'restore-emacs-pdmp)
           (delete 'strip-double-wrap)))))
    (inputs
     `(("libxaw" ,libxaw)
       ,@(alist-delete "gtk+" (package-inputs emacs))))))
--8<---------------cut here---------------end--------------->8---

Ideally, we would reduce the LLVM and Mesa closure sizes as I started
doing some weeks ago.

-- 
Pierre Neidhardt
https://ambrevar.xyz/