Ideally, yes, but it’s not required.
Some people who are already selling a product go through Business Labs and discover they need a different product that will perform better. Others come into Business Labs with no product at all and follow our process for creating and testing one from scratch and do just fine.
Either way, by the end of Business Labs you will need a product or service. Maybe your current one is the right one already, maybe it’s not. You’ll figure that out through Business Labs.