Some search gives that esp32_technical_reference_manual says:
Multiple-channel scanning mode; there is a pattern table that defines the measurement rule for each SAR
ADC. The scanning mode can be configured as a single mode, double mode, or alternate mode.

But API for pattern table has a lot of ...

Sorry, I don’t quite understand what the program code will look like allowing you to simultaneously record more than 2 ADC channels while using 2 I2S.
I mean in the i2s_adc_dac example one ADC channel is recorded using one I2S.. Is there any ability to simultaneously ascque 3-4 adc channels with ...

I have several ESP32-WROOM-32В. Vref of ADC is factory calibrated. hall_sensor_read () returns a value from -19 to +56 (depends of module ).
The question is why are the zero values (only Earth magnetic field) ​​different on this modules?
What are the measurement units of hall_sensor_read (), zero ...