There are bottle shops in PA where you can get individual bottles or six packs. They are called "licensed beer stores" in the law. I believe they require a full license [might be wrong], so they're often attached to bars, but don't need to be. They are much more common in college towns.
There are also "beer distributors" [not the same as "beverage distributors"] who sell beer both by the case and by six-pack. Beverage distributors may only sell cases or kegs. They may also sell water and non-alcoholic beverages.
Wine and liquor may only be sold by Commonwealth of PA State Stores.
And regular payments to certain politicians.