Now that I look, a Guix port could use much of the same underside of Nix, the derivation recipe format is the same: http://git.savannah.gnu.org/cgit/guix.git/tree/README#n128
The problem is that I interpret the format differently than on unix, which is not so bad, because Genode derivations are always marked as such. I use the environment variables section to rewrite requests for ROMs and File_system. It was a better solution than assuming that derivations must be built with Noux, and its less work to write a few variations of a Noux wrapper at the higher level than it is to make Noux work everytime at the C++ level.
I'm still not that interested in Guix, but, if someone could port the Guile/Guix evaluator, I would help hook it to my store and builder components. What would be really helpful is if someone could come up with a good system of distributing binary packages that would be compatible between the two.
Emery