Has an NFL game ever ended 23-0?
Yes. NFL has seen a final score of 23-0 43 times. It first happened on October 9, 1921, when Akron Pros beat Chicago Cardinals, and most recently on December 16, 2018, when Indianapolis Colts beat Dallas Cowboys.
That makes 23-0 the 131st most common final score out of 1,090 that have ever occurred in NFL. One point away, 24-0 has happened 64 times and 23-1 has happened never.