In my definition of "low level" I don't exactly mean the base linux packages but rather a base package nearly all linux distros have that's not interfaced or used by most "average users"
Some linux distros (such as Fedora and Debian) patch ssh to link against libsystemd-notify to enable it to send systemd notifications and interact with other components libsystemd-notify then links against xz and other libraries
Ah, so xz wasn't actually something in use with SSH at all but rather added code that used the systemd-notify to know when to execute that separate code?
Inb4 linux distro with patched SSH with "Commercial grade easy access remote support!" with a picture of a dude smiling with a headset that only has one speaker