Seems no reason why it wouldn’t work, except that the comparator output won’t be the quantized CV, the output of the DAC will. And I don’t know how fast you can make it, but I’d guess fast enough. On the other hand, a microcontroller based solution might be simpler to implement (or might not!). I have a quantizer built around an Arduino Nano
though it’s intended to be much more general than this, quantizing to arbitrary scales rather than solely to equally tempered chromatic.
Just thinking aloud: Would it not work to just use a suitably configured ADC chip followed by a DAC?