If Momo ended up taking that knife he saw on the ground while he and Kanjuro were en route to Orochi, who does he try to stab first?
For me, it’s Kanjuro...Momo’s hatred for the shogun runs deep and has been long held even across a trip through time. His anger for that man may outstrip whatever animosity he holds elsewhere, BUT - Kanjuro was a confidant of his father, a man who (seemingly) did everything to protect multiple generations of Kozuki, and then turned coat at the most crucial moment of their revenge. His fury at the absconded Scabbard is still new and red-hot, so I think his first concern is eliminating a new enemy before turning his attention to the old one.
Now, the kid is still just eight years old, so how effective this plot would be against grown men remains to be seen. Just think it’s something that will come up soon - like Chekhov (kinda) said, if you introduce a knife in act 3, you gotta use it by the time Luffy and the alliance show up to challenge Kaido.