I recently fell into the Linux from Scratch rabbithole. The extra unexpected fun came while attempting to build LFS from within NixOS (my daily driver, which I only had a basic proficiency in). I quickly realized the challenges of following the LFS project's guidance, due in large part to how the Nix store is implemented. So I fell down another rabbithole of learning derivations and the Nix language - which took me a good way though building the LFS toolchain within Nix's intended sandbox. However, achieving FHS-compliance became another issue as I attempted to build essential LFS system tools within a chroot-like environment, but sought to do so in roughly the same declarative/reproducible manner as Nix's ideal. After a few lost hairs, I discovered the wonders of Nix's FHS build environment/bubblewrap implementation. A few hoop-jumps later, handling permissions and migrating to the final build partition, the project was complete with a mostly declarative, mostly reproducible, functional, minimal, bootable LFS build.

What sticks with me most through this experience is the brilliance of the open-source community (and a special satisfaction with now being able to say "I use nix btw")