QFC used to make seltzer water flavored like root beer, Dr. Pepper (it was called "Hint of the Doctor Flavor which is downright hilarious), and cola. The product line was discontinued due to lack of popularity and I miss it every day.
I wish that some of these manufacturers would bring back product and sell it online. There's gotta be room for products that have enough global popularity to support a market, even if no one local grocery store does enough business to make it worthwhile.
Walmart does an IMHO pretty good pretty good delivery-to-door service that leverages their existing logistics network. Amazon does groceries if one buys Amazon Prime.
I regularly get Diet Dr. Pepper delivered by Walmart, which I would have thought would be impossible to do economically -- it's heavy and low-value and they only charge a fixed shipping fee, no matter how much you get -- but apparently they can do it. They have to at least have the ability to get it to their store, so...shrugs. And beyond that, they can do delivery-to-store service, so if they have a guaranteed sale and someone just wants to pick it up, I'd think that they could swing that for products that only have limited demand.