It might also be worth saying where you are as the models that turn up in different parts of the world can be different so location can be a clue.
Absolutely!
"Sopranelli" isn't the name of any actual maker - but it could well be the brand name of an importer somewhere in the world. The name sounds made-up, possibly a conflation of the most famous Italian maker's name "Soprani" with "Gabbanelli" - especially seeing that the badge on it has strong similarities to
Gabbanelli's badge.
Otherwise, I can only find two references to Sopranelli-branded accordions on the internet - one that has been for sale in Mount Cotton, Queensland, Australia, and another in the hands of a player named
Jordan Kostov on YouTube, only his one is closer in style to Scandalli's Super VI professional model...
I wonder if the brand might have something to do with the onetime dispute over the use of the Gabbanelli name in the USA?