The Netflix Original Christmas movie is now a genre unto itself, its ranks expanding every year by the flimsy, tinselly dozen. What its identifying aesthetic features are — and how you might distinguish it, say, from a Hallmark or Lifetime variation — is a tough question: You’d have to remember any single one of them a season later to say for sure. Some have Christmas princes, some have Kurt Russell, but almost all of Netflix’s yuletide offerings blend seamlessly into a cheer-by-numbers mass, as sweetly bland and textureless as non-alcoholic eggnog. There’s nothing especially wrong with that, or with “Operation Christmas Drop,” an anodyne, friction-free romantic comedy that faintly distinguishes itself from its snow-sprayed genre brethren with enticingly balmy South Pacific scenery. If nothing else, it gives viewers something to daydream about while they keep half an eye on its story.