I've done this several times.  Actually, in a couple of cases I added
an accordion it its own separate case that I designed to sit on top of
the piano.  The advantage to this is that the same suction supply that
plays the piano can play the accordion.

On the Piano/Pipe organs, unless you wanted to use A rolls, you might
consider OS and NOS, (organ series and new organ series) rolls made for
the Reproduco Piano/Pipe organs of the Operator's Piano Company.

These rolls are not rare and many of them have some excellent
arrangements as did the "O" rolls made for the Coinola pianos of the
same company.

Hal Davis