Has an Euros game ever ended 14-0?
Exactly once. On November 18, 2023, France beat Gibraltar 14-0, and no Euros game before or since has ended that way. When it happened it was a scorigami, the first 14-0 in league history.
That makes 14-0 the 28th most common final score out of 34 that have ever occurred in Euros. One point away, 15-0 has happened never and 14-1 has happened never.