Android Source Code
https://android.googlesource.com/
https://cs.android.com/android/platform/superproject/main (searchable)
Framework
https://android.googlesource.com/platform/frameworks/
https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/core/res/res/values
SDK Samples and APIDemos
https://android.googlesource.com/platform/development/+/master/samples
https://android.googlesource.com/platform/development/+/master/samples/ApiDemos/
System Apps (Java and Kotlin)
https://android.googlesource.com/platform/packages/apps/
https://cs.android.com/android/platform/superproject/main/+/main:packages/apps/ (searchable)
AndroidX Code (Jetpack and Compose)
https://cs.android.com/androidx (searchable)