> would propagate about the same right?

No. Free space loss increases with frequency.

FSP loss for 915 MHz at 10 kms is ~ -111.67 dB while for 2.4 GHz is -120 dB.

That is a 9 dB loss which is significant. It could mean the difference between a copy or just plain static though the LoRa is supposed to be copyable down to -140 dBm.

The max tx power is around 150 mW (21.76 dBm), so at 10 kms, the RSSI is 21.76-120 = -98.24 dBm which is above the -140 dBm limit.

This calculation is assuming there is no loss due to vegetation or humidity or other barriers.