What's the hypothetical hardest Star, Shine, or Moon you can think of? I think if the Darker side of the Moon had a Daredevil Run, and Mario could have only taken one hit for the entire course, including the Bowser segment, I think that it then would have gone from the easiest final challenge in a 3D Mario of this decade, to by far the hardest. Alternatively, since Odyssey had no 1-hit Daredevil Runs, I think a more realistic take on the final challenge would have been if there had been no hearts in the level at all, and Mario could only withstand three hits (that did not refill at the final segment). I think the challenge would have been a lot more difficult then, but I still don't think it would have been the hardest grand finale challenge.
If the Boss Blitz Galaxy had had a Daredevil Run instead of just a timed challenge in Galaxy 2, that may have been the ultimate nightmare. But they didn't.
If the Boss Blitz Galaxy had had a Daredevil Run instead of just a timed challenge in Galaxy 2, that may have been the ultimate nightmare. But they didn't.