The earliest mechanical sound effect that I recall was fitted to some Tri-ang locos, and was probably based on the traditional card in the bike wheel spokes of childhood memory. I have heard of a piece of string in the coupler striking a bit of metal plate as it rotated, and was once asked how I got my engine sound a long tome ago when the "secret" was a misaligned motor.
The standard ESC became standard mostly because the vast majority found that operating that way was so simple, intuitive and natural. Being different has it own rewards, but carries its penalties as well, in this case, the lack of extras designed to work with it.
If you are into electronics, I am sure that it is possible to hook some sort of circuit into the speed control output. The signal there would be the basic PWM pulse rate plus whatever the motor was doing related to its speed of rotation plus the average voltage applied. Between them something acceptable might be found, and, if derived before going to the reverse contacts, would be proportional to speed and work both forward and reverse. Much like the string and plate.