Is it possible to get the GZ curve from the software?

Yes. In FLOATSOFT, you can get this curve by enabling Lateral Righting Arm calculation in the Settings menu, and then running Iterate Through Heel mode from 0° to 180° with a 10° step (or as required). When calculations are finished, plot the curve by selecting Lateral Righting Moment in the Graph drop-down menu (below the results table), and click Show Graph. Before running calculations, make sure you input the correct CoG Coordinates, so the results are valid.