There shouldn't be much danger if you follow the instructions, but i'm not responsible for any damage you might do to your device.
I can't guarantee that this script will work on every device.
Make sure to read the script, don't just blindly run random scripts off the internet. :)
Never try to delete your chroot container, without unmounting it first, and rebooting your phone!

Things you need before you can run the installer:

• A rooted android phone
• Termux
• Git
• Wget
• Bsdtar

Open Termux, and install the required dependencies, you can skip this step if you already have them installed.
pkg upgrade
pkg install git wget bsdtar

Download, and then run the script as root.
git clone https://github.com/selirra/anarch
cd anarch
su
bash setup

You will be asked for an installation path, the size of the created disk.img file, and whether you want to mount your internal storage in the container.

If everything went okay, once the setup script finishes, you should have a working ArchLinuxARM chroot container.
You can now create a password for the root user with passwd.

You will find the mount, unmount, and start scripts at "/your/installation/path/anarch"!

• Create a password for your vnc server with vncpasswd
• To change your vnc server's resolution, run echo "geometry='your_desired_resolution'" > ~/.vnc/config.
• Run vncserver :0 to start your vnc server.

• Run ssh-keygen -A.
• Run echo "PermitRootLogin yes" >> /etc/ssh/sshd_config to enable logging in as root via SSH.
• Enable and start the sshd service with servicectl enable sshd and servicectl start sshd.
• Connect to your device via ssh with ssh root@"the_device's_ip_address".

• Edit "/etc/locale.gen" with the text editor of your choice, and uncomment your desired locale.
• Run locale-gen, then run echo "LANG=en_US.UTF-8" > /etc/locale.conf. (replace "en_US.UTF-8" with the locale that you uncommented in locale.gen)
• To make the changes permament, run echo "unset LANG" >> /etc/profile and echo "source /etc/profile.d/locale.sh" >> /etc/profile.

• Run ln -sf /usr/share/zoneinfo/Zone/SubZone /etc/localtime, make sure to replace "Zone" and "Subzone" in the command.
• This is an example: ln -sf /usr/share/zoneinfo/Europe/Budapest /etc/localtime

• Xfce, LXDE, and Plasma works without major errors.
• After installing Plasma, run echo "export $(dbus-launch)" >> /etc/profile.

• To get around systemd's limitations in chroot, i used Smaknsk's servicectl utility.
• https://github.com/smaknsk/servicectl