It's all cool man
It being his own chakra wouldn't support it.
A. It's raw chakra forced, which has completely different properties than chakra molded by the user.
The average shinobi is garbage, but only 100 could make attacks that you can see from space.
B. It being his own chakra isn't it, because that's the
sum of his chakra.
It's not like he uses all of his chakra at once.
And in case I need to prove that, like you said under
So Naruto definitely doesn't use all of his chakra, which means the sum of this feat wouldn't scale to him.
You're 100% correct, but you instantly die in a case like that. Kakashi didn't have enough time to do anything except probably talk to Choji.
And for that part, it wouldn't take that much chakra to save you. Naruto didn't put all his chakra in Guy when he ran out of chakra against Madara, it was only a little bit, so the fact that Sakura (who has more chakra than a clone of Naruto) needs to put in almost all of her chakra just to heal him says a lot.