The pairing of salty pork with sweet fruit has existed since the 2nd century AD for the very simple reason that it's delicious as fuck.
Prosciutto and melon, figs and parma ham, Orange glazed ham, caramelised onions and hotdogs, gammon and pineapple....
And irn bru square sausage.
Love all of the above. Not pineapple (possibly melon too, not tried) on pizza though for whatever reason.