This is the code I use to run Debian on my Android device.
The file packages.txt was generated by running get_packages.sh in a Debian machine.
Install Termux
Open the app and in the terminal run:
apt update
yes | apt install proot openssl wget binutils
wget https://raw.githubusercontent.com/donno2048/Debiandroid/master/setup.sh
chmod +x setup.sh
./setup.sh
Open Termux and run (you might need to exit Termux and open it again):
debian