Lenova 11e - Chrome OS updates at EOL - compatible OS?

Our elementary school can no longer run accelerated reader quizzes and I-Excel on the 11e chromebooks. If I follow Mr.Chromebox instructions for FullRom firmware - what OS would be best for the 11E hardware limitations - ChromeFlex or Windows(version?) ? Or is there a trick to force the chrome OS to continue updating after EOL?

Board name?

HannStar J MV-6 2514 94v-0 E89382

Thats not a board name

The Model is GLIMMER D4A-E5V-B2Q-A5I

You can install a Linux distro on your Chromebook. If your Chromebook is too slow to run DEs like GNOME or KDE then you can look up lightweight Linux distros / DEs.

You may not have fully working stuff if you install ChromeOS Flex.

Flex will have issues on that.

Thank you!