Hi.
You are right. In our examples, the messages are not encrypted because we haven’t found straightforward solutions and we didn’t want to complicate the examples.
I haven’t tried encryption, but there is a library to encrypt LoRa messages with the ESP32. I hope this is useful:

• https://github.com/Kongduino/hw_aes_esp32

Alternatively, you can also use LoraWAN (the messages are encrypted):

• https://github.com/mcci-catena/arduino-lmic

I hope you found these resources useful.
Regards,
Sara