There's a comment in the Guix source (added by the author of that first post you linked, Ricardo Wurmus) that seems to indicate that they found a way around the segfault problem described in the post by using a registerised version of GHC:
https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages...I had to look up exactly what this means, not being very familiar with the Haskell ecosystem myself. It looks like it's not the raw source form and is architecture-specific, but it's also not the compiled binary form. So that's not perfect, but better than relying on the compiled binaries I guess. (Unfortunate for me since my laptop is ARM and I'd like to be able to use git-annex, haha.) But this seems to work for older versions of GHC.
This post by Simon Tournier from last year describes the current situation near the bottom, and from what I can tell this is still correct: https://simon.tournier.info/posts/2023-10-01-bootstrapping.h...
> The bootstrapping problem for Haskell is not solved. And Ricardo works hard on it. Currently, from the older GHC around (4.08.2), which relies on gcc-2.95 – part of the Bootstrapping story above – it is possible to chain until version 6.10.4. Then versions 6.12.3 and 7.4.2 are not packaged yet for completing the Haskell chain from version 4.08.2 to modern version as 9.2.5; fully connecting the dots with bootstrap-seeds and dropping these 450MiB of binaries. The solution of this chicken-or-the-egg is not yet complete.
