Thank you. I've found the repository at

GitHub

GitHub - marmot-protocol/whitenoise: The White Noise Flutter App

The White Noise Flutter App. Contribute to marmot-protocol/whitenoise development by creating an account on GitHub.

and will later study how to integrate inside geogram. For the moment the geogram private messages are really private since they are hosted directly inside the devices of users, rather than untrusted devices. But I'm quite sure we'll need this at some point.

Is someone here still using XMPP?

Arrived to my house a recent Heltec LoRa ESP32 to match the model that @Memo is using. Pretty soon we should have a good firmware ready for LoRa, WiFi and BLE integration on geogram.