Is this specific to Debian?
Nope, but Debian does use systemd by default so it's there.
I'm running Arch Linux and /etc/machine-id is present.
There's also an optional /etc/machine-info file that could exist. It's not a part of systemd and won't be created by default. It's more of an informal way to have details about the system in 1 spot. It was more popular when provisioning bare metal servers but still has value in the cloud. You can have key / value pairs on who to contact, where it's located, what type of machine it is, etc..
FreeBSD has it as well.
https://www.freedesktop.org/software/systemd/man/latest/mach...
https://dbus.freedesktop.org/doc/dbus-uuidgen.1.html