Here is the info on the wiring tool used to apply overlays.
I haven’t used this hat, but the sensors should be available as files in /sys/class/iio/devices. To read the adc built into the potato, for example, (1.8v max btw): cat /sys/bus/iio/devices/iio:device0/in_voltage0_raw
Google “Reading from Linux iio devices” for more on that.