Disagree that it's cheaper to retrofit quality household ventilation compared to changing stove types.

The cost of the heat exchanger alone is likely to exceed the cost of entry level portable induction cookers. Now add in costs to run ducting, cut through walls, seal the penetrations etc.

Of course, things are different at scale, and there's no reason we can't have a world where quality household ventilation, and less-harmful cooking stoves are both mandated.