[pxc]

Guix is niche, but it's very much 'real software'. It does useful things well, and it solves some problems that very few competitors adequately do. It's used for reproducible scientific computing on some HPC clusters, which is a pretty cool niche if you ask me.

The Guix package collection is also sizeable and growing exponentially-- within a few years, it'll probably outgrow most Linux distros in terms of size.