gRPC is a good thing, and I found that I can use it on Android, both client and server, so I plan to build a gRPC server in my app for IPC.
The question is that what are the disadvantages of building a gRPC server on Android?
2024 update: For Android IPC, gRPC Java 1.42.0 in 2021 released support for a Binder-based transport. This is able to integrate well with Android and supports passing Parcelables in Metadata. It would be an alternative to AIDL.
For IoT, gRPC Java 1.49.0 in 2022 released support for io.grpc.OkHttpServerBuilder, an Android-optimized HTTP/2 server.
Original 2017 answer: gRPC Java does not support any server for Android.
That said I have tried running Netty on Android and it worked at the time. I'm pretty certain TLS would not work for some Android versions.