It was so small that a solo developer reimplemented the entire kernel.
https://www.reddit.com/r/emulation/comments/hygtnx/mesospher...
https://github.com/Atmosphere-NX/Atmosphere/tree/mesosphere-...
https://www.reddit.com/r/emulation/comments/hygtnx/mesospher...
https://github.com/Atmosphere-NX/Atmosphere/tree/mesosphere-...
Er, what? Why would a 3rd-party reimplementation allow Nintendo to use their work?