In their fridges and freezers.OK who is developing home energy management systems that also provide freezing and refrigeration? Can existing fridges and freezers be adapted to provide some heating and hot water?
Is anyone extracting heat from bath water, waste water and waste heat from washing machines and dishwashers and tumble dryers? Condensing tumble dryers?
There are passive means of heat recovery from used shower water. They don’t work for baths as the idea is to transfer heat from the outflow to the inflow.
I can’t see that active heat recovery would ever be economical from such heat sources as they are too intermittent. If economic, to you, means money, it need not be the case. It could equally be carbon.
The only exception from your list is heat pump tumble driers which could have their exhaust airflows switched between into the house in winter and out of the house in summer (wet days only, of course).
Normal refrigerators / freezers were actually one of the first type of domestic appliances considered for DSR in the UK. There is quite a long history of proposals around it. National Grid (in)famously came up with a scheme which would mandate that domestic fridge/freezers had a control installed which would manually turn them off if measured grid frequency dropped below a certain level. Whilst an entirely reasonable idea it was deemed a ‘big brother’ initiative by press and shelved.