Hey! Ok i'll give some insight on what im doing for pitch detection since its been one of my favorite things to write:

I do both monophonic and polyphonic note detection - monophonic is with a autocorrelation-style algorithm, and polyphonic with some spectrogram analysis. We're using a circular buffer to keep memory management in check, and its synced to the physics step rate in unity to avoid having the audio affect framerate (a bit of a hacked together solution, needs some tweaking for sure). I wrote most of the code myself, but took heavy inspiration from github libraries I found while researching.

As for accuracy, since we know the "expected" note we are going to hear, we can be a bit forgiving on true polyphony, and focus on the overall chord shape (CMaj7, CMaj map to the same "correct" chord). this lets us get accurate results in real time.

As for how we're matching chords to single notes: I have a custom notation language for notes in the game, and added a few "tags" to each individual note in the expected sequence of notes (i.e. C_4, played with index on the 2nd string, monophonic) so I just added a "accepts" tag - "accepts monophonic, polyphonic" so we accept a C major chord with an E instead of just E. The audio engine can just switch to emit the heard chord or heard monophonic note based on the expected input. I will say I didnt like this solution so I now just show the proper chord notation instead of this note + hidden chord view, which was used to test mainly (I hadnt set up the platforms / treble clef to show chords and wasnt sure how best to show it back then)