Simple soft power latching circuit for a microcontroller
why this kind of simple and useful IC doesn't exist and how is it implemented in consumer devices? (or alternatively, am I bad at searching?)


And you proceed to list an IC that fits the bill. The MAX16054.
Press debounced button to enable, hold button to have MCU issue CLEAR.

I've made this on a project using a single flip-flop from a 4093.


Which has as benefit being a very standard stock part, compared to any Maxim part.



You circuit should work, but there might be issues with the thresholds for the EN pin since the resistors are very high, compared to leakage of the mosfet and diode. This might need fine tuning.
You should test it.