My suggestion is for flutes, when activated for a certain mode to do this, will play the sounds of nearby flute noteblocks. This would allow flute players to join our noteblocks and Create steam whistles in performances. The flute would play the sound of any activated flute instrument noteblock in a certain area (8-16 block width cube maybe). This should include covered noteblocks as well so the flute can be the only source of the sound.

MehVahdJukaar's idea was to use echo shards and have the new flute (sculk flute thing) grab notes and other sounds.