Seeking Assistance for Implementing Offline Message Sending and Receiving on Android Using ROS

Hello! I want to use this project to build my own Android application. My plan is to use the Java layer in JNI to write ROS publisher code and use the C++ layer algorithm (GVINS) to receive it. The entire Android project will run offline, without an Internet connection. Could you tell me how to achieve this using ROS-Mobile-Android without removing ROS?