Ada can't bootstrap? Ironic...
Coreboot is the only option, but it has a hard requirement on Ada because that is what they wrote their intel graphics stack in.
It is a real mess.
Ada has had even less progress and I am not aware of any writeups.
TL;DR: Ada and Haskell need to have compilers implemented a language that has a full source bootstrap path such as C, Go, or Rust that implement just enough features to compile the official compilers.
If you know anyone that takes this on and succeeds I have a 2k cash bounty for them, and we can likely find others.