A lot of the processing steps expect linearity and would have to be reworked for floating point or log scale data. Most HDR sensors are using some kind of logarithmic compression for sensor readout, but I've never really heard of a floating point adc. Google seems to suggest tbey're not readily available.
Yeah there isn't, it's not that simple, even at sensor level to have that much dynamic range
A linear ADC with enough range is usually fine, you can do the math later. But maybe for this case it needs a non-linear element before the ADC? (no idea how log recording needs anything at the HW level)
