Inclusive b to u l nu at Belle/Belle II

The importance of measuring inclusive V_{ub} by studying charmless semi-leptonic decays at Belle and Belle II in order to address the inclusive vs. exclusive puzzle is discussed. Various difficulties involved in the measurements such as separating signal from the dominant B to c l nu background and the effect of using different theory predictions for signal and background modelling are introduced. Lastly, projections for global model-independent data-driven fits, which will be carried for the first time at Belle II, are shown.