How to install ChromeOS to your USB stick for your old PC

(1) Prepare an USB stick with at least 16G. I am using 64G for demo and you need this size to download and install Linux in ChromeOS. Your PC should x86_64 based computer with UEFI boot support and ave Intel gen 1 to 9 to download rammus recovery image. For detail requirements see here https://github.com/sebanc/brunch.

(2) For Windows OS, first install WSL2 and Ubuntu 20.04 and you must enable this in "Turn On Windows features on and off"

(3) Alternativey, you can use Linux machine with Ubuntu 20.04 to do this

(4) According to the Brunch USB guide The ChromeOS recovery image is based on your CPU of your PC.
For Intel
"rammus" is suggested for 1st gen -> 9th gen.
"volteer" is suggested for 10th & 11th gen.
11th gen (and some 10th gen) may need kernel 5.10
For AMD
"grunt" is suggested for Stoney Ridge & Bristol Ridge.
"zork" is suggested for Ryzen.
Ryzen 4xxx devices need kernel 5.10 when Brunch Framework boot up

(5) After setting up the Ubuntu user and password run these scripts to create the image file (e.g. rammus for USB 64G drive)
sudo apt update
sudo apt -y install pv cgpt tar unzip
mkdir rammus
cd rammus
wget https://github.com/sebanc/brunch/releases/download/r97-stable-20220121/brunch_r97_stable_20220121.tar.gz
tar xzvf brunch_r97_stable_20220121.tar.gz
wget https://dl.google.com/dl/edgedl/chromeos/recovery/chromeos_14388.61.0_rammus_recovery_stable-channel_mp-v2.bin.zip
unzip chromeos_14388.61.0_rammus_recovery_stable-channel_mp-v2.bin.zip
# 64G USB has only about 58G for actual usage, so the size parameter here is 58.
sudo bash chromeos-install.sh -src chromeos_14388.61.0_rammus_recovery_stable-channel_mp-v2.bin -dst /mnt/c/Users/Public/Downloads/chromeos_rammus_58g.bin -s 58


(6) Then use ChromeOS Recovery Utility to flash the images, Use local image in Settings and select the "C:/Users/Public/Downloads/chromeos_rammus_58g.bin" image. See here

(7) If you are lazy to create this image, you can use mine and download it from chromeos_rammus_58g.bin.zip (3.61GB). You don't need to unzip it for creation of USB flash drive in ChromeOS Recovery Utility or Rufus

(8) If your PC has secure boot enabled, either disable it (ig you have set the supervisor password) or import the key from USB. To enroll the key directly from a USB, select OK -> Enroll key from disk -> EFI-SYSTEM -> brunch.der -> Continue and reboot. Moreoover, enable of UEFI support and change the boot order to USB is needed in BIOS.