Looking at this doc: https://github.com/wix/Detox/blob/master/docs/APIRef.Configuration.md
It says that the
Build command (either xcodebuild, react-native run-ios, etc...), will be later available through detox CLI tool.
I'm trying to setup the build command to work with Android. Am I supposed to add react-native run-android to the build command? What do they mean by Detox CLI tool?
The build field is optional, and should contain whichever execution logic needed in order to have the .apk file set and ready in the path specified in binaryPath. You are more than welcome to refer to the Detox example project, which was set up as a reference exactly for these type of questions.
In any case, from the react-native CLI tool's help: react-native run-android = builds your app and starts it on a connected Android emulator or device. That makes it not very suitable, as we typically want to build the app, and have detox launch the emulator (optional) and install the app on the device(s), as needed.