How about the nuclear button?

I’m curious where you personally draw the line.

Using a nuclear strike first on the whim of an individual POTUS?

First use should be heavily debated and almost always avoided.

In response to {immediate pressing life threatening conditions at scale} .. they can be discussed and game planned well in advance and voted on - even if that vote is limited to a large pool with a breadth of military and diplomatic experience.

The current US practice of "POTUS can, like, do whatever" is pretty tragic.