I've seen it for sale in at least a couple of bars in Copenhagen.
A bar owner I know here says selling these more-premium sodas is a good way to make a bit of extra money on people who aren't buying alcohol — you can charge more for Fritz-Kola than for Coca-Cola.
A different bar owner I know chose Jolly Cola, avoiding an American product but keeping a low price.
One of the Colas that tastes good enough to replace Coke in my experience.