According to RISC-V Android SIG, RISC-V Android GitHub Repo has been set up as RISC-V Android Source · GitHub.
Further work on Android will all been added to this repository. Currently, it includes all RISC-V changed android source code to build riscv64 image for RISC-V android emulator.
Here is the commands to download the android 10 RISCV code:
$repo init -u firstname.lastname@example.org:riscv-android-src/manifest.git -b riscv64-android-10.0.0_dev
the build target is “aosp_riscv64-eng”