When comparing Kali Linux vs ChromeOS Flex, the Slant community recommends ChromeOS Flex for most people. In the question“What are the best operating systems for old laptops?” ChromeOS Flex is ranked 19th while Kali Linux is ranked 21st. The most important reason people chose ChromeOS Flex is:
This is basically just Chrome OS which already runs on Cheap chrome books. It works well for web browsing and file storage on low end computers.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Better than ParrotOS, BackBox for hacking purpose
Contains too many tools for hacking. Those tools are not already included in BackBox or ParrotOS.
Pro Standard pentest tool set
Pro Live session distro used for forensics
Pro Lightweight and fast
This is basically just Chrome OS which already runs on Cheap chrome books. It works well for web browsing and file storage on low end computers.
Pro You can try it via bootable USB
Cons
Con Not intended to be a daily driver
This distro was written for pen testing and security work. It is not meant to be a day-to-day OS (unless that's your job).
Con Very old packages
E.G. Firefox's current version is 61 but Kali linux consists of its 52th version. Though kernel is not that old.
Con Limited hardware support
There is a list online of about 100 or so computers that officially support Cloud Ready, but it can also work on a laptop not on that list, results may vary.
Con Only really meant for web browsing
To use the software, you need to have a Google account and log in. Because it's meant for web browsing and researching, you won't find software like Steam, Office, Adobe Photoshop, Aftereffects, etc; or even a 3rd party browser other than Google Chrome.
Although there are plenty of alternative web browser online, and in the Chrome Web Store, which is still supported by Chrome OS.