Looking for gyroscope drift spec in datasheet
BMI088 is offering a wide acceleration measurement range (up to  24
  g), high vibration suppression ratio and vibration robustness, as well
  as high bias and temperature stability. The automotive-proven
  gyroscope of the BMI088 has an unmatched bias stability of less than
  2°/h and a low temperature coefficient of offset (TCO) below 15
  mdps/K.


Source: https://ae-bst.resource.bosch.com/media/_tech/media/product_flyer/BST-BMI088-FL000.pdf

I don't think I would believe that either unless listed in the datasheet. Only the temperature drift is listed in the datasheet. You would have to know the internal workings of their Kalman filter and how the errors of the gyroscope are being integrated to be able to calculate this yourself. The best course of action would be to contact Bosch and ask them about the drift rate and to put that figure in the datasheet.