Sampling analog pin of nrf52840 adafruit feather express at >30kHz

I'm trying to sample electret microphone connected to analog pin A0 on nrf52840. I originally wanted to use I2S microphone but there is no library support for it on Arduino nor on circuit python. I can't use PDM mic due to firmware specification so I'm using an electret mic, analog. I require the sampling rate to be at least 30k but in Arduino I see that the function AnalogRead takes 100 micro seconds, that's 10,000 time per second. I need at least 30k so i'm planning to direct the ouput of mic into 3 analog pins on board and create a timer that's 30kHz bit-depth 10bit or 12 bit and samples each pin once every 100ms. I have no clue what timing library there is I can use to control this sampling function.

Alternatively, any good methods for collecting high quality audio data from analog pin?

I'd also like to do some testing on speed and audio quality so I'm looking to make this function take a sampling frequency, bitdepth, buffer array, and record into the buffer at the specified rate and depth.

connected to analog pin A0 on nrf52840

I don't know anything about that thing...

so i'm planning to direct the ouput of mic into 3 analog pins on board

I don't know it that will work with your hardware but the ATmega chip on a standard Arduino has only one multiplexed ADC so using more pins wouldn't make it any faster (and with stereo you get half the sample rate, etc.).

And, the ATmega chip is a little slow and it has limited memory so it can't do much real-time "audio processing", and it generally can't transmit/receive Bluetooth and process continuous audio at the same time.

Do you know of any timing library or clock that I can use to set a fixed sampling rate of some sort to test this out?

Also if analogRead is limited to 100micro sec and only 1 multiplex ADC, how are arduinos oversampling at 16kHz audio? Doesn't make sense to me

Also if analogRead is limited to 100micro sec and only 1 multiplex ADC, how are arduinos oversampling at 16kHz audio? Doesn't make sense to me

Are you sure this is the speed that the nrf52840 does its A/D conversions?
You can set a timer to sample analog values up to the maximum sample rate of the SAADC (200 ksps) On this chip.

I thing you read things about the Uno and other ATmega chips and get confused.