Endeavouros onto Chromebook
Having tried Manjaro I decided to give Endeavouros a go and the same problem, with a similar fix.
I then booted this on the Chromebook and the install worked until installing bootloader failed.
The solution is to open a terminal and enter
chroot /tmp/calamares-root
Hint: use tab to complete the numbers after root
Then retype the failed command and add
--no-nvram --removable
Hint : If you leave the installer error visible you can copy and paste into the terminal (CTRL+SHIFT+V)
This works without error.
Then type
sudo grub-mkconfig -o /boot/grub/grub.cfg
Then run the cleanup script
chrooted_cleaner_script.sh
and then
exit
Reboot and all should be good.