I ordered my remarkable2 yesterday. Wrt sheet music, Not exactly what you were talking about but there was a great app called jammit that did something similar

I ordered my remarkable2 yesterday. Wrt sheet music, Not exactly what you were talking about but there was a great app called jammit that did something similar --playing along with sheet music with existing songs, and either isolating the instrument or muting it. The app just disappeared one day and the community reverse engineered the app and you can still get it under the facetious name "crammit" on Mac and windows. I found it very helpful to learn drum set notation.