I dont have HVAC specific advice for you, but I’ve lived in a well isolated house in a hot environment (42C max temperatures) and what we did was open basement windows and atic windows, and have a fan point out of the attic window. This created a draft that exhausted the hottest air in the house out, and while upstairs was always hotter than downstairs, it was much more bearable than without.
I imagine a similar setup would help you get the cooler air from downstairs up, and a big advantage is that you can try it with very little cost and commitment.
I don’t know how your house is configured, it might not be a solution for you. We have a pretty habitable attic, not those insulation filled dens I see in American houses, so it was pretty easy to try it for us.
Also, we opened and closed the windows every day, we didn’t leave it open overnight.
This depends on where you live in. AFAIK, in Europe dishwashers are not even hooked up to hot water, just cold. In America their standard plug electricity is weaker and therefore it’s not enough for a dishwasher to heat the water hot enough to sanaitze.
This is the reason electric kettles are not a big thing in America (they take significantly longer to heat the water) and “home electrification” is a bigger deal there.
And as always, to anyone interested, Technology Connections talks about this in his videos on dishwashers, induction stovetops and kettles.