I wanted to share this, after trying so many different forks. For anyone interested in using crouton to install Arch, refer to this fork of chroagh. I tried/edited about 4 other forks, but this buried beauty has actually allowed me to install aarch64 Arch within Chromium.
Since it's outdated, you'll likely need to run sudo enter-chroot -n [chroot name] -u root in order to be able to login/finish setup.
Since it's outdated, you'll likely need to run sudo enter-chroot -n [chroot name] -u root in order to be able to login/finish setup.