Recommended · for some experience
#101 Long lasting DIY "Amazon Dash Button" using an ESP8266
Why people recommend it
Recommended Andreas Spiess video on a MOSFET latch that lets a microcontroller hold its own supply on after a button press, then cut it off when finished.
Watch for: Note the small off-state leakage he measures
In their words
I am trying to implement something similar to this:
Bogd on electronics.stackexchange.com, May 2018. CC BY-SA.