Great question — answering as the UphillTech team:
You need to enable Developer Mode in order to save changes. Modern ChromeOS devices can be put into developer mode by pressing specific keys while ChromeOS is booting. From here you can log in as the root user chronos . Then start the command prompt through VT-2 by pressing: Ctrl + Alt + → , or through crosh ( Ctrl + Alt + T , then run the shell command). The developer mode shell is basically just bash, complete with sudo commands. Read through the linked document for how to make the filesystem writable (to save changes), how to leave developer mode, usage examples, etc.: https://chromium.googlesource.com/chromiumos/docs/+/HEAD/developer_mode.md
Full answer by Cpt.Whale: https://superuser.stackexchange.com/a/1809423 (CC BY-SA 4.0).
Need it done for your business? UphillTech.