ESP32 Hall Effect Sensor

I'm playing around with an ESP32. It has a built-in hall effect sensor.

First, I'm wondering which pin this is connected to. It is accessed via the Hallread() which doesn't have any set-up so I assume that it is part of the ESP32 library I'm using. I'm assuming that it is connected to one of the ADC pins, but it doesn't show on the pin-out diagram. Is it one of the pins that isn't brought out to the header pins?

Second, what chip is being used? I'm wondering in case I want to get another such hall effect sensor to use. Sometimes having a range is better than on/off.

A quick look at the ESP32 reference and it looks like the hall sensor is built into the silicon and outputs using SENSOR_VP & SENSOR_VN that are on GPIO36 & GPIO39 respectfully.

So, on that diagram I linked to, anything that is yellow or dark blue is already connected to something. That means that:
4, 15 & 16 are connected to the OLED
36 & 39 are connected to the hall effect sensor
TX & RX are connected to the USB
32 & 33 are the external crystal
2 is the LED
0 is some button
37 & 38 is some CAPVP/VN (whatever that is)

Val42:
So, on that diagram I linked to, anything that is yellow or dark blue is already connected to something. That means that:
4, 15 & 16 are connected to the OLED
36 & 39 are connected to the hall effect sensor
TX & RX are connected to the USB
32 & 33 are the external crystal
2 is the LED
0 is some button
37 & 38 is some CAPVP/VN (whatever that is)

Probably not, some pins on chips have alternate/specific rolls other than digital I/O and the different names on each pin denotes an alternate function that pin can perform. As an example pin 12 can be a digital I/O pin (GPIO12), and analogue input pin (ADC2_5) & a touch input pin (TOUCH5).
TX, RX, 0, 4, 15 & 16 are connected to external devices but without a schematic it's difficult to say if/what is connected to the other pins.