It is really good practice for independent hands. I loved struggling with this, I can really recommend it for the good feeling when it goes well. It does make me ralise how little I know about bellows technique, but one thing at a time.
Accordion lesson 19 Golden Brown - YouTube youtube.com
With this accordion diagrams you can check how many white and black keys has 12, 24, 32, 48, 60, 72, 96, 120 bass piano accordion. If you're wondering what is X bass accordion keyboard range and which keys are available then you can find answer here.
Matchmaker Song A simple arrangement for piano players who have taken up the accordion (easy accordion chords but with some chromatic movement for interest). Right hand has simple tune but also moving inner part.