Reading 32 ADC channels
Analog Devices makes an 8 &amp; 16-channel simultaneusly sampled ADCs with 12 and more bits, but the results are still read out one channel at a time.
Use their filtering to pick one and use 2, 3, 4 of them.

https://www.analog.com/en/products/analog-to-digital-converters/standard-adc/precision-adc-20msps/simultaneous-sampling-ad-converters.html