There are several software packages and tools that can be used to interact with all NISAR products except L0B RRSD data. L0 level data is unprocessed and has very limited viewability.
Instructions for working with NISAR L2 and L3 data formats in ArcGIS, QGIS, and Panoply are provided in ASF’s Work with NISAR Sample Data documentation.
The documentation also provides guidance for using GDAL command line tools for these tasks:
Getting Sub-dataset / Group Paths
Convert from NISAR H5 to GeoTIFF
Reproject a Single Subdataset from NISAR H5 Data
Reproject an Entire NISAR H5 Dataset
Clip a NISAR H5 Dataset to a Geographic Extent
Create a Multiband GeoTIFF with a NISAR Dataset