Propagation (FSPL) is a lot better at 868/915 Mhz than 2.4Ghz. What is the advantage to have a "super BLE", that can propagate for few hundred meters?

Not much. While this is technically LoRa on 2.4GHz (which is not new), most people will associate LoRa with significantly longer range and LoRa 2.4 can do.