I'm also hypersensitive to smells. I know about bowls of vinegar, but find I can't stand the smell. I can tolerate lightly scented candles, and will light one of those occasionally. If anything has a strong scent it gets banished outside. Somehow I don't find the smell of brownies baking offensive.

For the litter boxes I use clumping clay cat litter and scoop as much as possible - usually after I've used the toilet and before I've washed my hands. I've found the kitties and I don't like the scented cat litters. Can't remember off-hand what cat litter I currently have. I do find the pine / ground corn husk / paper / compostable litters not worth it - they don't hold a clump very well, so the pee goes through to the pan bottom.

Now if I can just convince Chloe that she doesn't need to dig a hole to the foundation in prep for her toilet time, it would be better. A little litter on the bottom helps absorb things.