Hi Ryan, the closest model in the Magenta repo we have to what you're describing is probably Improv RNN, which is now several years old:
https://github.com/magenta/magenta/tree/main/magenta/models/improv_rnn
There are a number of caveats. The model only accepts chord symbols as harmony, so if your harmony is arranged you'd have to somehow infer chord labels. It also doesn't handle pitch bends; currently none of our symbolic models do. And it "improvises"; it doesn't look at future chords when deciding what note to play.
But it might be a reasonable starting point.
-Ian