Not sure I'd be using Cube, or trying this as my first outing with STM32 + LoRa
With the original LRWAN / Semtech libraries you'd need to create two radio instances to run it from a single MCU.
LoRa Point-to-Point type communications or LoRaWAN ?
If these are two separate STM32 + SX1262MB2CAS stations, perhaps look at the PingPong examples, reworking one into a Transmit only, and the other to a Receive only station.
