https://github.com/fosslinux/live-bootstrap/blob/master/part...
The steps go from a binary seed of a few hundred bytes to (almost) gcc. It is still being actively developed as part of the Bootstrappable Builds project:
https://www.bootstrappable.org/
https://github.com/oriansj/talk-notes/blob/master/live-boots...
https://github.com/oriansj/talk-notes/blob/master/live-boots...