NDB in the US is almost unheard of anymore. I don’t know a single pilot that willingly flies an NDB approach. I am not sure there are any NDE approaches still published in the US. And VOR in the US is being slowly phased out as well. As a side note, HIWAS is being ended in January. I don’t know of any GA aircraft that are manufactured in the past 20 years that had NDB as standard equipment and DME in modern aircraft is pretty rare (true DME, not the GPS substitute.)

I wouldn’t say “most aircraft” rely on NDB — at least not most IFR-certified aircraft actually flying. It’s pointless to use it. ILS and RNAV are by far the most common. NDB approaches aren’t required anymore on an instrument checkride.