galaxy flyer:
GNS 430--no way, at least at RNP 0.3 or less. At RNP 0.3, equipage requires on IRS sensor, minimum.
GNS 430 is a TSO C-145-146 sensor, which cannot really perform even to RNP 0.30 as expressed for RNP AR.
As to RNP AR an IRU (or IRUs) is not required for RNP 0.30 provided the missed approach does not require RNP of less than 1.0. But, the required intregity and alerting for "entry level" RNP 0.30 is well beyond the performance of a unit like the GNS 430. On the other hand, the GNS 430 can fly LPV, which is well beyond the performance of the most demanding RNP AR approach for the last 1 mile, or so, of the final approach segment.