Not sure if something like that would even support x86 or C99, so would probably still need an older mainframe and early GCC source tree. Could probably get by with a virtual emulator for the former.

Would be good to cross post this to:
https://programming.dev/c/nix

I could imagine bootstrapping via Bell Labs Unix from the 90’s would be more authentic, yet demanding LFS experience. I wonder how far back computer historians could bootstrap up to a modern compiler for integrity and verification purposes?

https://www.owlfolio.org/research/bootstrapping-trust-in-compilers/

https://www.theregister.com/2025/11/07/unix_fourth_edition_tape_rediscovered/