Taken from the CompTIA IT Fundamentals Exam Guide book (2nd edition, published 2021). I'm not sure if they fixed this in newer versions, if at all.
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
Aren't their embedded systems that run the Linux kernel without the core-utils (maybe with busybox instead) and would therefore be non-gnu linux variants?
Yep, Alpine Linux does this as well.