Tie point grid(lat, lon) extract using gpt

I found the way to extract tie point grid(lat, lon) by snappy.
But, I wonder the method to extract or export the gird from the original file (*.xml or *.h5, etc) using GPT

Or can I export the SAR image bands to geotiff with latitude and longitude layers?
As I know, when applying the terrain or ellipsoid correction, I can select output bands (lat, lon, incidence angle) in processing parameters.
So, I mean if I can do the similar processing in original data without geometric correction using gpt.

Can anyone help me?
Thank you!