Following Prot’s Emacs: commands in popup frames with ‘emacsclient’ made sense for me. Like irreal, I struggled with doing this but Prot’s approach _just works_™. 2 adjustments tho: full executable path needed for #emacsclient on #MacOS #KeyboardMaestro & the server config needed to change:

  (use-package emacs
    :ensure nil
    :defer 1
    :config
    (if (and (fboundp 'server-running-p)
             (not (server-running-p)))
        (server-start))
    )

Don’t know if this will help others. #Emacs is an app, a journey, AND a destination.