Project/Product Homepage: https://nuetzlich.net/gocryptfs/, https://github.com/rfjakob/gocryptfs
Why we should include this into the repository, i.e. what does it do that the alternatives do not?
To provide an alternative to EncFS and replace it in the future.
gocryptfs is the aspiring successor of EncFS  which is in the process of dying and has several major issues  which still are not fixed and probably never will. EncFS' development began in 2003, when cryptographic standards weren't as developed as they currently are and the head developer pretty much abandoned the project and recommended gocryptfs back in 2017 .
gocryptfs is also very cloud storage friendly in the way it doesn't split files into smaller encrypted files, so uploading goes at high speeds, hence, provides good performance  and has been audited .
Is it open source?
Yes (License: MIT, https://github.com/rfjakob/gocryptfs/releases/download/v1.7/gocryptfs_v1.7_src.tar.gz).
I'm also be willing to submit and maintain a patch, if gocryptfs gets accepted.