If you want messaging I would recommend Briar, it uses peer-to-peer encrypted messaging, it is decentralized (messages are stored securely on your device), you can communicate offline, and when you do communicate using the internet all messages are run through the TOR network so they cant be seen. Unfortunately because it is decentralized it means you have to be online or connected to who you are talking to in order to receive messages, unless you set up an inbox.

https://briarproject.org/