The project is no longer maintained but Oversec had a cool concept of hiding your own encrypted text as non-printing chars in Android text fields in any other a

The project is no longer maintained but Oversec had a cool concept of hiding your own encrypted text as non-printing chars in Android text fields in any other app, like e.g. WhatsApp. https://github.com/oversecio/oversec https://github.com/oversecio/oversec