[gentoo-user] What files does GNU Emacs 27 load on startup on Gentoo, and in what order?

[akater]

Info node “The Emacs Initialization File” mentions

- init.el which is described in enough detail

- default.el which is found via “the standard search path for libraries”
  — what would that be?

- site-start.el instead of which Gentoo has site-gentoo.el (I guess) —
  but when is it loaded and how does Emacs know to load site-gentoo.el?
  and why isn't it compiled?

- early-init.el, “loaded before the package system and GUI is
  initialized” — is it loaded before or after site-gentoo?

And does Gentoo load anything else, by chance?

Finally, is there a difference in what files are being loaded between “rc-service
emacs.user start” and just “emacs” in user's shell?