The story
From fire + work. Compare Saterland Frisian Fjuurwierk (“firework”), West Frisian fjoerwurk (“firework”), Dutch vuurwerk (“firework”), Low German Füürwark, Füerwark (“firework”), German Feuerwerk (“firework”), Danish fyrværkeri (“firework”), Swedish fyrverkeri (“firework”), Faroese fýrverk (“firework”).
Etymology from Wiktionary, CC BY-SA 4.0.