What’s RNAV got to do with GPS?
We have had RNAV long before the first satslite ever went up!
That is true. I remember during the 70’s RNAV was the new thing in aviation and the FAA was pushing RNAV routes using INS. Unfortunately, not enough aircraft had INS to make development of RNAV routes worthwhile. So it sort of died out until GPS came along and the FAA resurected the term RNAV and applied it to procedures using GPS.