I think pure isnt about the body being modified. Maybe its the mindset. Definitely not about if u ate someone or killed cause if so then it was a impossible mission from the start. Unless its going for a twisted ending. But maybe the way to reach the peak and get to the end is either sacrificing ur close comrade you bonded with over the countless hardships or finding the team in a sea of people who stab you in the back to get it themselves.
I like this take too!
Or even the thing about only one person being able to go through potentially being a lie. . . and you can only go through if you have genuine bonds that showcase your humanity in the face of adversity.
I have the feeling that at the end, in order to pass through the gate, you must be "pure", meaning you cannot have your body modified