I built a CMOS inverter with an NDP6020P and an NDP6020, which have a VGS of -1V and +1V respectively.
The output of the KA75330 goes to the input of the CMOS inverter, and the output of the inverter goes to the enable pin of the voltage regulator.
Just two MOSFETs, the voltage supervisor IC, the voltage regulator and the ESP32, nothing else.
It cuts off at about 2.75V instead of the expected 3.30V, but after cutting off the ESP32 was still trying to boot as I could see its built-in LED flashing very briefly about once or twice per second, as if it was boot looping. I stopped the test when the battery was down to about 2.10V.
I suspect that the P-channel MOSFET was still conducting when the N-Channel MOSFET started to conduct.
If I use a P-channel MOSFET with a higher VGS (about -3.00V?), would it stop the battery from being discharged when the N-channel MOSFET is conducting?
I still can't explain why it cuts off at 2.75V, but it's better than nothing.