> In Void, which is using Runit, enabling a service (like alsa, crond, cupsd, etc) is a matter of creating a symlink, which feels very transparent and reliable.

It's exactly the same in systemd, although people usually use systemctl. It will report what it does:

  $ sudo systemctl enable sshd 
  Created symlink /etc/systemd/system/multi-user.target.wants/sshd.service → /usr/lib/systemd/system/sshd.service.