Arbitrary stuff like /etc/issue for several distros and occasions (I tinker about with several VMs, so there's that...)
But why only \S ? Help, I identify my server OS with /etc/issue
See, there's the mistake. Identifying through issue is not reliable, and has never been. And you can still continue to cheat yourself by putting whatever text inside. Lel.
Or try something meaningful instead.
Contains no logo, but some strings I use e.g. for VMs to have individual base information at a glance. More dedicated systems like hypervisors bear less information in the issue.