Hey Franco_Kun,
https://gdevelop-app.com/game-example/spatial-sound/ might be what you're looking for. It allows sounds to be 3D in a 2D environment.
The example has sounds played in a direction, or in your case left/right ear.
Local folder + raiDrive https://www.raidrive.com/
Other user has access to a cloud drive of your choice, you both have a live updated folder. Should probably still work on separate versions and manually merge, but at least data wont get deleted as you both have raw project folders.