I've generally seen it for embedded systems due to smaller size and you can statically link it.

But there are some compatibility drawbacks for non musl binaries as well as source that intentionally or unintentionally relies on glibc behavior or non standard functionality.

You don't want to mix and match your libc's on a running system.

Buildroot may be a good way to start to play with musl (or uClibc, another small c library).