nss-gk-api is intended to provide a safe and idiomatic Rust interface to NSS. It is based on code from neqo-crypto, but has been factored out of mozilla-central so that it can be used in standalone applications and libraries such as authenticator-rs. That said, it is primarily for use in Gecko, and will not be extended to support arbitrary use cases.
This is work in progress and major changes are expected. In particular, a new version of the nss-sys crate will be factored out of this crate.