Vintage Bandoneon/Concertina/Chemnitzer built in electronics

Description

For sale is what we believe to be a Vintage Bandoneon and/or Concertina and/or Chemnitzer 2 Switch with Electronics.  There is no manufacturer marks on the inside or outside of the instrument.  From what we were able to "google" and some input from other people it appears to be a GEM. Unfortunately, I can not guarantee any of the information as we do not have any local people who can seem to tell us about them. The item is definitely vintage and in functions as intended, even the electronics.  We plugged it into an amp and the sound port did function.
Now during our research apparently there is a lot of information on upkeep and tuning that is done to these instruments.  We can not tell you the last time it was serviced or tuned.  It was bought from a customer who stated it sat in the closet after a parent passing and never moved. We have looked and looked and could not find a definitive way to find out what key it is tuned to.  We tried the guitar tuner and ect.. but kept getting different reads.
We are selling as is with no guarantees as this is a unique item for us, have exhausted all our research capabilities, and do not have extensive history on it.
Come with a hard case made for it.
Please do not think we are ignorant on the item it is just tuff to find a lot of information out there or someone local with knowledge.