The actual performance of MLPs obtained from PiNet2-P3 is shown in Fig. . As compared to DeePMD, PiNet2-P3 does not only reproduce the correct concentration-dependent densities (Fig. ) but also the modulation of the water structure in concentrated electrolyte solutions (Fig. ). To go the extra mile, we have applied this set of MLPs trained with PiNet2-P3 to calculate the ionic conductivity at 330 K with the Bussi-Donadio-Parrinello thermostat. The predicted ionic conductivities of the NaCl solutions (obtained from the diffusive regime of the corresponding polarization mean squared displacement) shows a very encouraging agreement with experimental reference in terms of both the concentration-dependence and the absolute value (Fig. in the Supporting Information), although it is much more challenging to converge this quantity at a higher concentration.