A fun little experience.
You got me to play again with your 9 coins tease (I did not expect the boss to be destructable).
It was odd to me, that the melon who was begging me to save it was used as a thrown weapon which gets smushed when hitting enemies or walls, as well as there being an unlimited supply of melons to throw.
I think it would have been a better idea to throw the melon in it's large form and it ricochets from the walls and then comes to a stop and you have to pick it back up again.
You could improve the level design with some very basic shape language guiding the player. I ran a lot in dead ends because there were no real indicators and a lot of the rooms were so large they did not fit on the screen.