The left hand has all the buttons on a piano accordion, but also has cheats. The second line from the top is the tonic and the top line is the third from that tonic. The tones go up by fifths along the length.

The third gives you the major chord of the tonic, the fourth gives you the minor chord, the fifth gives you the dominant 7th, and the sixth (on the one I owned) gives you the diminished 7th. So you have automation for chord accompaniment and rarely have to play anything of significant complexity on the left.

Which leaves the bellows and half a piano on the right. 🤣