The following steps were followed on Ubuntu 26.04 beta version running linux 7.0.0-10-generic
Before proceeding, unlock the Pixelbook's bootloader and install Coreboot firmware as explained in the amazing documentation from Mr Chromebox.
Then, proceed with the normal Ubuntu installation from a USB stick.
You should also install Git with sudo apt install git.
A reboot after each step is advised.
Out of the box, the Wi-Fi card will not be recognized by the OS.
Edit /etc/default/grub by adding pcie_aspm=off to GRUB_CMDLINE_LINUX_DEFAULT.
The resulting line should be something like
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=off"
Then run sudo update-grub
Credits to Reddit user olm3ca.
The brightness will keep adjusting continuosly in a very annoying way, disable brightness auto-adjustment.
Run
gsettings set org.gnome.settings-daemon.plugins.power ambient-enabled false
Follow the instructions provided in the amazing chromebook-linux-audio repo
Copy-paste @flantel's .hwdb as detailed here
If you want, change the # KEYBOARD_KEY_5d=controlpanel line to KEYBOARD_KEY_5d=delete to use the "Hamburger" button as delete.
Then run
sudo systemd-hwdb update
sudo udevadm trigger