The fact that Nestle still exists should be proof enough for anyone that it literally doesn't matter how horrible a large corporation is. There is no activism route to correcting these companies behavior. Only legislation with teeth will work. That we'll all collectively decide to stop doing business with bad companies is nothing but a libertarian fantasy.

Let's leave aside "not at all," because that's often not a viable option. Let's also remember, we're talking about reaching net zero emissions. For instance, where do I buy carbon neutral food?

You can't materialize those alternatives if they don't exist. And, when we're talking about making things in more sustainable ways by emitting less carbon, because carbon externalities aren't accounted for, the sustainable way is more expensive than the dirty way. So, capitalist corporations being the profit maximizing machines that they are, inevitably choose the dirty way.

Then there are the energy inputs to account for.

See also this comment by another user: https://news.ycombinator.com/item?id=35630362