Android/data/com.v2ray.ang/files/assets(path may differ on some Android device)
Android project under V2rayNG folder can be compiled directly in Android Studio, or using Gradle wrapper. But the v2ray core inside the aar is (probably) outdated.
The aar can be compiled from the Golang project under AndroidLibV2rayLite folder. For a quick start, read guide for Go Mobile and Makefiles for Go Developers
v2rayNG can run on Android Emulators. For WSA, VPN permission need to be granted via
appops set [package name] ACTIVATE_VPN allow