Beers on "nitro" are still carbonated with CO2. The nitro is used to achieve a higher serving pressure used to force it through a diffusing nozzle on the tap. N2 doesn't actually dissolve in liquid very easily compared to CO2. If you put the CO2 at higher pressure, it makes the beer more carbonated over time.

It might be nice but it's a completely different product and not desirable for many styles.

CO2 increases acidity, changing the taste. Nitrogen doesn't do this.

See "chemistry" section of https://en.wikipedia.org/wiki/Carbonated_water

On the note of nitro craft beers, more often than not I find that nitro tap beers are a gimmick and that the beer would be better served be being conventionally carbonated.

It's the same story with cask ales. Some styles really don't work well on a handpull.