Listen, I use guix so I'm not against you, but claiming that Guile, or even any scheme / lisp, is a transferable skill is a stretch 😛
As a software developer for 20 years, configuring guix is the only time I've encountered guile. And the only time I've used any kind of lisp is when I forced myself to during a coding challenge or advent of code thing, just for interest's sake.
So again, I know what you're saying, but for me, deep in the industry, guile might as well be a bespoke language for configuring guix 😅
Yeah! I was just coming here to recommend GuixSD or NixOS! Not because they're normal, but because they're not, and you have an opportunity to screw around 😅
Fedora and Debian are different but also pretty similar. Arch or Gentoo are more different. The atomics like bazzite and silverblue are even more different. And then there's NixOS and GuixSD that are basically a completely different paradigm of how to setup a system. And that might be frustrating if it doesn't work for you, but as a test computer go wild! Heck, try NixOS and GuixSD to experience their differences from each other!
The only other thing I might recommend for a challenge is something like Linux From Scratch where you don't have any distro and you just build everything yourself. Definitely not recommended for normal people! It's a project rather than something you can just try out for a weekend. And it may be frustrating, who knows. But if you're into that kind of thing it may be enlightening!