Termux is open source. I fully agree with you on the one that provides the rooting mechanism, as I believe that's normally closed source.
Good luck on reading and vetting all that code.
And then installing Android Studio (It is a beast!) to compile the code into an APK.
And don't forget to repeat the two steps every time there is an update.
Termux is open source. I fully agree with you on the one that provides the rooting mechanism, as I believe that's normally closed source.