This project is open source on Github:
https://github.com/0ldMaid/P2P-Messenger

P2P Messenger is a peer to peer messaging app that allows for direct end to end encrypted messaging transfer. Unlike traditional messaging apps that are sometimes encrypted but still go though the company's systems, this application allows users to communicate with each other without going though a central server. Messages are delivered directly to the end user without any middle man. What's the catch? it's slow, and there is only basic functionally no calls or videos.

This application is much harder to use then your standard messaging app. Tor is difficult to use and difficult to manage. If you are not a "tech" person this app is NOT for you. That being said, make sure you, at the very least, allow app "unrestricted access" to battery usage. Otherwise every time your phone screen turns off the server will be closed.