With the newest version 0.14, the general support of EGM2008 for geoid correction of DEMs has been added. However, in the function pyroSAR.snap.util.geocode, the EGM that is applyied to an external DEM if externalDEMApplyEGM=True, is hardcoded to EGM96:

if dempar['externalDEMApplyEGM']:
get_egm_lookup(geoid='EGM96', software='SNAP')

It would be nice if in a future version an option is added to pyroSAR.snap.util.geocode, in wich the user can choose which EGM will be applied to the external DEM (EGM96 or EGM 2008), just like this is now the case for pyroSAR.auxdata.dem_create.