Here comes an update for interested people:
-Emlid confirmed the IMU inside ReachRS2 is no longer the MPU9250 but it is replaced with the ICM20948
-Basic read/write over SPI with the IMU was successful.
-As an initial step, I’m trying to implement a ICM20948-driver for RTIMULib (accel/gyro seem to work already)
-after everthing is working with RTIMULib, I’ll try not to use it 
. But attempt to use the DMP embedded in the ICM20948 to reduce the load on reach itself.
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