I'm far from having something presentable right now. I still have a lot of things to package first, trouble shoot it, and make a bootable image (or at least, a container).

First of all, this is not MY distro, I'm working with dcat on it, but for now we're both experimenting here and there before working together on the same goal. It will be statically linked against musl, installable in under a minute (so easy to bootsrap) and will focus on minimalism and simplicity, both for the maintenance and the tools.

musl is s standard C library, like newlib, glibc or dietlibc. Simply put, it's what provides "stdio.h" and friends, as well as printf(), open(), malloc(), ... You get it.
The most used libc in glibc (the GNU monster). It's huge, and contains a lot of bugs (because of its size). It also tries to implement more features than necessary, which could lead to more bugs.
musl libc is simpler, stronger and smaller. So it's a good candidate for stability and security. You're right, alpine linux use it, and void has a musl-based image (not the default one).

So yeah, using musl is a preference, as glibc is free too.