The wizarding community would be shocked. Guns are not part of their world, and for Harry to use one to kill Voldemort would be unthinkable for many. There would be outrage from some traditional wizards who believe in magic as the only proper way to fight.
Most of the fandom would probably be horrified. Naruto is known for his positive values, and killing a family member is completely against that. There would likely be a lot of criticism towards the author of such a fanfic.
Makima's fate in the manga is quite complex and involves a series of dramatic events. She faces powerful opponents and has her own agenda that leads to significant developments.
Well, Makima's death in the manga is the result of a series of events and confrontations. It's not straightforward and is tied to various character interactions and plot twists.