It looks like Netcdf4 is based on HDF5 ([https://en.wikipedia.org/wiki/Hierarchical_Data_Format)](https://en.wikipedia.org/wiki/Hierarchical_Data_Format\)). But it doesn't look like grib2 is based on HDF5. Although their usage cases are the same.
That said, if you think the HDF5 library could load up grib2s, I'm all for it. HDF5 looks much more modern than a lot of GDAL's file-loading functionality.
