Not sure why someone would want to try it. It’s basically just Chrome OS but more limited, https://support.google.com/chromeosflex/answer/11542901?hl=en

Some of these are really severe - no CD/DVD support? Really?

Also more concerning, is that Chrome OS Flex might become unsupported soon, as per https://www.zdnet.com/article/google-might-abandon-chromeos-flex-next-heres-why/

For the technically minded trying to keep up to date and secure older hardware, a good GNU/Linux distro seems like the best choice. And it’s not so hard to set up a good Kiosk if setting up the older hardware for a less tech minded person, https://oofhours.com/2023/05/02/creating-a-kiosk-with-linux/

That said, although I haven’t tried it myself, I found a good story about someone’s success with Flex, over at https://www.zdnet.com/article/i-revived-three-ancient-computers-with-chromeos-flex-and-you-can-too/