Another Hohner Harmonette (1902) was a "mouth accordion," made for the Spanish market. It had 5 small megaphones attached to the reeds, 10 keys (buttons), 20 reeds, 2 bass keys, a box and a trumpet mouthpiece. I'm guessing that it was a blow-only instrument.
Actually it was a blow and draw instrument, like a diatonic button accordion. I cannot play the button accordion, I always mix up when I should squeeze or pull the accordion. Curiously enough, it was very intuitive for me to play the mouthaccordion. Both instruments have the Richter tuning like a harmonica.
Cheers, Fernando