OK NSS is ground only. So you need a relay, or else if you are using an aftermarket shifter, AKA Hurst etc some of those have a series wired type switch. But even those are "light duty" switches, and need a relay. Modern Mopars like hemis and Magnums used Bosch style relays so that would work.
So NSS really is only going to serve my need for reverse lights? It won’t really interrupt starting circuit? (Unless adding in a relay that closes when the NSS grounds)