I’m guessing that the chocolates are made from two “half bottle” molds. In other words, two (lengthwise) halves are created, the liquor-syrup mixture is added to one of the halves and then the other is placed on top and is “sealed” by a little bit of chocolate.
And yes, many of those candies are the “real deal”. I remember that one store in the tourist-trap town of Helen, GA was busted for selling them. The county Helen resides in allows for beer and wine sales only, and apparently the sweets contain enough liquor to meet the state definition of an “alcoholic beverage” - which in GA is actually quite broad because it defines said beverages based on whether they’re fermented or distilled and not by a specific alcohol content. That’s why teenagers cannot buy “near beer” in GA because the law says under 21s cannot buy fermented beverages, not “a drink with .01% or more alcohol content”.
Of course, many of those candies use artificial flavors instead of actual alcohol - they’re not all the same.
I don’t know about the half-bottle approach. I haven’t ever had these liquor-filled candies, but I have had some Ferrero ones with espresso syrup in the middle. (Yes, they were delicious.) The inside was almost completely full of syrup. I’m guessing the syringe method, then covering up the hole in chocolate.