It's possible to bootstrap GCC starting from only a 357-byte binary seed:
https://github.com/fosslinux/live-bootstrap
You're right, it also requires a Linux kernel, and of course, you also have to trust the hardware you're running it on. Still, it reduces the amount of stuff we have to take for granted as trusted, which I think is a good thing. (I'm not involved in the project, just an admirer).
[1]: https://github.com/oriansj/bootstrap-seeds/blob/b09a8b8cbcb6...