Pardon me, I'm sort of a casual Linux user and I have no idea what people are talking about. What are GNU Guix and Shepherd? A cursory glance at Wikipedia makes

Pardon me, I'm sort of a casual Linux user and I have no idea what people are talking about. What are GNU Guix and Shepherd? A cursory glance at Wikipedia makes it seem like they're GNU alternatives to the apt-get and init/systemD I've been on for awhile. I'm outside of my Debian comfort zone, apologies for my ignorance! What's significant about this?