Ground augmented GNSS landing systems are able to provide CAT III guidance, however they are not yet certified except for some very rare test installations.
The big thing about those systems is cost effectiveness as one ground installation is enough to serve nearly 60 runways with non precision and precision approaches within a radius of 40 to 50NM. That makes it far cheaper than the conventional precision approach aids that require an independent installation for each single runway direction. So there is a big drive to develop those systems although there are still some major obstacles especially in terms of reliability (jamming etc).
And RNP is commonly used for Required Navigation Perfomance which is something we all have to use throughout our normal operation for at least the last 15 years. Pure RNAV approaches are described as thus in europe and ground base augmented GNSS approaches are usually abbreviated as GBAS approaches.