Termux is an Android hacking app designed to make it easier to work with the Linux-based open-source Android operating system. Termux also provides a graphical interface to access the operating system’s resources, which are managed by the user-installed Linux packages, and to communicate with the rest of the Android OS.
Also, read Game hacking apps for Android.
You don't need to install Termux mode apk because Termux is open source and you have nothing to buy. It's completely free and will be updated regularly when you download it from the Play Store. Check the list of best GBA emulator for iOS.