So it looks like the root uuid might be generated, but from what I read vfat uuids are translated from a partition serial number that isn't manipulated in the guix source so getting uuids beforehand might be impossible.
Both the root and efi partitions get a label, so I might be able to use those to identify the partitions. They're both hardcoded, but the former is unstable (was changed earlier this month) and the definition that exposes it (root-label) isn't exported... I think my best choice here is to forcibly import "root-label" and duplicate the hardcoded "GNU-ESP" in my config, but if the latter changes I'll get an error at runtime rather than build time. How would disk-image work in the first place? It doesn't look like the generated GNU-ESP or / are added to fstab automatically (checking the output image).
