Right now, I don't have much dedicated to Chrome OS. This is because Chrome OS is really that simple or easy to figure out. I do have a bit with using the Linux container under Chrome OS; that is on the crostini page.
Oh, and before anyone complains that Chrome OS isn't really "Linux", stop. Just stop.
For newbies, especially parents getting a Chromebook for their children, the first GMail account logged into the device after purchase is the "owner" of the device. I suggest for younger kids, that the parent be the first one to log in. What age that changes all depends on the parent and the child. ;-)
Hints & Tips
This isn't only Chrome OS, but whose going to pick a nit. So most of this will also work on CloudReady by Neverware. I use both a lot, but haven't tested each item on both Chrome OS and CloudReady.
Clear SSH keys in Secure Shell chrome app:
Removing Chrome OS
The school were I work got rid of lots of Acer C731 Chromebooks. This device is no longer receiving new versions of Chrome OS. I think that is a bit of a waste because even though some were heavily used it, they seem to still have life in it.
Anyways, I grabbed one with missing keys to play with. And what do you do with a laptop that was abandoned? Put Linux on it! You could try Chrome OS Flex on it, but my experience is the sound is always busted with old Chromebooks. At the bottom are more comments, but for spoilers, only Bunsen Labs performed well.
One last thing before going into the steps to take. Make sure you truly understand what the instructions are doing. It's okay to take risks, but understand what they are! Especially if you are using these instructions for another Chromebook.
Reload Chrome OS: Better said, do the recovery process. Even though folks say don't do it for phones, you are better off doing it here. Especially if you are using a device that was deprovisioned from any type of enterprise Google domain. Follow Google's "Download a new copy of the OS" instructions.
Onboard Process: In short, log into the Chromebook after recovery. If the device was once part of an enterprise Google domain, you will have to to reset the domain settings. Especially if they disabled Developer Mode.
Enable Developer Mode: Google has this page, but there are different options. Sometimes depending on the device. For the Acer C731:
Power-off the device.
Hold ESC + REFRESH, power on the device. Let go when you see the "Missing or Damaged" screen.
Press CTRL + D.
Press ENTER to confirm. NOTE: Doing so will erase everything on the Chromebook!
Wait until after Chrome OS resets itself (about 10 - 15 minutes).
After another reboot, booting will pause on a "page" saying "Press SPACE to re-enable". DO NOT do this as it will get you out of Developer Mode.
Wait 20 seconds and you will get to the setup or onboarding screen again. But in a developer enabled version of Chrome OS. You DO NOT need to go through this if you just want to install Linux or CloudReady.
Get a command prompt: Now press CTRL + ALT + FWD (basically where F2 is located) to get a Linux prompt (yes Chrome OS is Linux!).
Log in with "chronos": No password needed.
Load Firmware: Go to MrChomeboox.tech's page on Firmware script to install the script. I suggest you read the whole website. Again, really know what you are doing.
Update the RW_LEGACY firmware: And reboot; I like to test things in stages. Meaning this is less intrusive and if it doesn't work, something else is up.
Check Firmware: After the reboot, wait the 20 seconds, press CTRL + ALT + FWD, login as chronos and run "sude firmware-util.sh" to see differences.
Power-off the device.
Write Protect Screw: If you device has one, open the device up and remove the "Write Protect" screw. Ignore references to Windows 10. ;-)
Firmware Again: Go through the process to get to running the firmware script again.
No Going Back: Be certain you want to NOT boot (an outdated) Chrome OS!!!
New Boot Firmware: If you said yes above, in the script's CLI, install "UEFI (Full ROM) Firmware". I suggest backing up the firmware; don't use Chrome OS recovery USB. After all the install/backup prompts, you will get back to the main menu.
Linux USB & then reboot: Plug in the USB for the EFI supporting Linux distro you want to install and then choose reboot.
Sign it worked: You should get a rabbit logo during boot, which is the new EFI firmware.
Install Linux: Read below for various distro comments.
Firmware, last time: After booting & installing Linux, go back to MrChomeboox.tech's page on Firmware script to install the script under linux. You might never need it now, but why not just in case? :-)
So what happened after all that? I first installed Lubuntu 22.04; the "30 second review" is that it was a mixed bag. The positive side of the spectrum is that local apps run quite well. Even heavy ones like Libre Office and Clementine, at the same time. The other end is that web browsers are known RAM hogs. Even after some optimization (swappiness, noatime), Chrome brought the C731 to its knees. Firefox faired better, though leaving YouTube Music running and checking email, the machine locked up in 10 minutes or so.
I already mentioned Chrome OS Flex. It performs well, but the sound doesn't work. Greedy, er, silly Google!
The only linux distro that I liked the performance was Bunsen Labs. Don't expect much. But I could have YouTube Music playing, check Gmail and then start browsing.