haha, I was playing classical accordion nearly 45 years ago!
They have been around for a long time. Mine was the Giullietti 140 bass model!
It was switchable from the "classical"
(or more correctly named Freebass mode - which turned the chord buttons into single notes) to the "stradella" or usual accordion configuration. I was the Australian Champ for one year hahaha! Not that there was a lot of competition out here back in those days