Android Studio
Google's workbench for building and testing Android apps, used to create the file you upload to the Play Store.
Like a workshop with all the tools laid out, Android Studio is Google's official program for making and testing Android apps.
Even with React Native and Expo, you use it to install the Android tools, run a phone emulator, a pretend phone on your computer, and prepare the file you upload to Google Play.
In practice, you install it, let it download what it needs, start an emulator, and use it to create a signed build, which means the app file is marked as coming from you.