Lora, especially on regulated bands that are the most used ones, is designed for very small, very infrequent messages. It isn't suited for real-time chat (nevermind secure) and so I think you can't really make it work while respecting transmission regulations.
There are lora modules that work on the 2.4GHz ISM band but then you probably need to consider whether Bluetooth is not a simpler choice if range is not the no. 1 concern.
There are lora modules that work on the 2.4GHz ISM band but then you probably need to consider whether Bluetooth is not a simpler choice if range is not the no. 1 concern.