it uses a combination of ninja files and shell scripts. all the tools necessary for building the apk has already been cross compiled and remains as a package in the termux repos(thanks). the shell scripts act as a meta build system, as that builds ninja files dynamically if files have changed. this gives me free parallelism and incremental compilation (i think so). this is definetely not a general build script for all android apps. if it needs to be built by my method, there are a lot of implicit hardcoded file paths, and the biggest issue being that the apps should rely only on platform apis(the ones available in android.jar).
do note that if it wasnt obvious from my tone or my profile, i am a beginner, who has no idea what is going on, so instead of doing push requests or bug reports, i would much appreciate if you just voiced your reasons down below and start a discussion, instead of doing technical stuff on github, i am still learning on how to use all of that. this is the first project that i am showcasing on the internet(only because of my friends forced me to).