Underpromotion to a knight does show up occasionally, in chess puzzles. And even a rook or bishop can be the right move, in extremely niche situations (i.e., where promotion to a queen would result in stalemate).
A few years back, I asked if it’d ever actually happened in a real game that there were two bishops on the same color, and it turns out that it has, a few times, as either a joke, a mistake, or an insult.