Volotea is flying only 319 (unfortunately, I loved the 717). The codeshare is only on specific routes (namely, not the domestic ones).

The fun fact is that Volotea on their cheapest fare allow 2 pieces in cabin (big + small item) but Aegean in their GoLight allow just one piece. That said, the mapping of fares from A3 to VO is done on either "Saver" category or "ComfortFlex". Both include checked baggage and the difference seems to be on the ticket change/cancellation possibility (there is also a "snack" category but it's said that it depends on the carrier. For VO codeshare on A3 operated flights, similarly the fare includes checked baggage.