This is a great question as it also helps to answer earlier threads about loading RCM products into SNAP (Reading RCM data problem). The GRD products can be imported in, but I have not been successful in getting the 30 m SLC loaded with the following error:
It is good to know that CP 5 or 15 m Stripmap SLC works, but my area of interest only has Compact-Pol ScanSAR 30m Resolution 125km
Looking forward to an update on this.