Think of it: it's a Unix system. Literally. A unix system with the usability that your grandma can use. It supports both commercial and open source applications. The year of the linux desktop folks have been trying this for decades.
EDIT: already downvoted to negatives. The Linux folks really don't like to be reminded of that.
Grandma doesn't use certified UNIX. She uses a UNIX-like system. Only the engineers who ran the conformance test use certified UNIX since it required what I would consider heavy modification to the shipped OS configuration.
the claim is that the linux community has been trying for decades to create a desktop with the usability that your grandma can use it. the implied claim is that they failed, which is of course nonsense. linux has caught up with the usability of mac os a decade ago, if not before that.
Sounds good, but grandma will need to disable SIP, run a few commands using sudo, and add a root account from the recovery system. It's Unix in the same way Windows 2000 was POSIX compliant, you just need to reconfigure the default system.
The Linux desktop is widely used all across the world in the form of ChromeOS and, if you count touch screen devices, Android.
EDIT: already downvoted to negatives. The Linux folks really don't like to be reminded of that.