(patch author, reviewer and committer)
rust-nitrokey-sys was added in the patch series <https://issues.guix.gnu.org/48671>, but if you download the source code, you'll see a 'libnitrokey-v3.6' directory that bundles libnitrokey.
The fact that it bundled libnitrokey is also mentioned in the README.md, in the second paragraph:
This crate contains a copy of the [`libnitrokey`][] library, builds it from source and links it statically.
Greetings, Maxime.
OpenPGP_0x49E3EE22191725EE.asc
Description: OpenPGP public key
OpenPGP_signature
Description: OpenPGP digital signature
