To expand on this, for Bitchat to achieve anything close to its advertised range, it truly relies on a high density of users acting as relays in an open environment. Without that, you're essentially just doing a direct phone-to-phone Bluetooth connection, which will be subject to all the typical range limitations because of: Walls, Furniture, 2.4 GHz Congestion, Phone Antenna Quality and Placement, Phone Transmit Power, Phone Receiver Sensitivity.
The whole point of Bluetooth Mesh is that messages "hop" from one device to another. To achieve a 300-400 meter range, you would need a dense network of active Bitchat users, with each user reliably within 30-50 feet (or less, depending on the environment) of another, like at a meet up or conference. Its kinda like skipping a rock with a note on it across phones so Alice can msg Bob from 350 meters away.
