Off-the-shelf discrete MOSFETs that leak < 1nA are not that easy to find. Really. And you need to read the fine prints and test it - usually that degrades rapidly with temperature, for instance.
With that said, yes, unless you have an extremely low duty cycle, what will matter is how fast you can wake up and what keeps running in this low power state. For that, ESP32 in general are hopeless, as an example.
But again, even so, I still fail to see with what kind of power source a difference of say 1nA or less will matter at all. If anyone can point me to an example of such power source, I'm a client!