This will guide you on installing AUTOMATIC1111/stable-diffusion-webui on Termux (Android) + PRoot Distro. Make sure that you have a high-end phone to actually make this usable. On my phone with 8GB RAM, launch the webui alone take at least ~ 2 GB RAM, thus making it impossible to load any model and process further.
First you have to install Termux and install PRoot. Then install and login to Ubuntu in PRoot