A typical problem of Orbit determination of LEO satellites using GNSS involves processing InterSatellitesRange with remote satellite being one of the GNSS satellites. But the BatchLSEstimator requires the constellation to be propagated numerically (instead of using GPSPropagator).

Since the Numerical propagation of the constellation requires PV data, which typically is unavailable (even with IGS final product). It would be a great feature to implement a separate propagator to interpolate the position solution from IGS data (as mentioned here: https://gssc.esa.int/navipedia/index.php/Precise_GNSS_Satellite_Coordinates_Computation) which can be fed into BatchLSEstimator to use for the orbit determination.