Just for completeness, here are a few more points that might help someone else:
1. for SNPP SST you need to add "proc_sst=1" to the command line to get it to generate SST output like:
l2gen ifile=$name.L1A_SNPP.nc geofile=$name.GEO-M_SNPP.nc ofile=$name.sst.L2.nc l2prod=sst par=$name.L1A_SNPP.nc.anc resolution=$res_num proc_sst=1
2. it is also useful to note that SNPP and JPSS1 satellites have different rhos_XXX sensors
SNPP: rhos_410, rhos_443, rhos_486, rhos_551, rhos_671
JPSS: rhos_411, rhos_445, rhos_489, rhos_556, rhos_667
because you will need the last three of these to generate the true color image.