Hello, you can take any piano score, the fingering is different (if it is noted on the score) but if you go to chromatic basses, I suppose that you already have a certain level on the accordion.You can also take accordion scores or simplified scores, you just have to put your chords or to break them down (arpeggios).
Good luck, at the beginning, it is not obvious at all, we are so used to the fact that the chords are ready made that it is a bit confusing, our left hand is not formatted for that when we had a traditional learning. Best regards Daniel