(updated versions of this document, plus more, live here)
This will show you how to get Guix running on WSL2.
We're going to go as "minimal" as possible, without starting off one of the readily available WSL2 distros.
Parts of this guide should help with understanding how to set up any custom distro on WSL, not just Guix.
Disclaimer: I'm a Guix nOOb! (hence going through the trouble of installing it on WSL2)