I haven’t tried NP for piano yet, but for orchestral instrument playback it is MUCH “smarter” than just using the literal MIDI data created by Dorico. That’s why it sounds so much better than other playback libraries with “no user tweaking required”. In fact the user guide says (correctly in my experience so far) that it works better with most of Dorico’s “humanized playback” options turned off.
For example if you play something simple like a major scale of equal length notes with no articulations etc marked in the Dorico score, the way NP plays it depends on the tempo (and possibly on the dynamics as well), in the same way that a human player would choose tempo-dependent bowing or tonging techniques, maybe different fingerings, etc.
FWIW there seems to be only one NP expression map for ALL instruments, so much of the “musical intelligence” must be embedded in the program code, not in the MIDI input. (That makes sense to me, first because it makes NP notation-program-independent, and second because reverse engineering expression maps etc would be too easy for competitors to do!)
Full disclosure - I have tried the NP harpsichord, and IMO it is by far the worst thing I’ve tried so far in the software - which might explain why I haven’t rushed to try the piano as well. If everything else had been as poor as the harpsichord, I wouldn’t have kept it on my PC even if it was free.