A lot of people have these in their houses already. Go to Home Depot some time and you’ll see lots of heat pump water heaters.

Sorry, didn't see any "kitchen fridge/hot water tank combo units" on their website. Care to provide a link?

Or perhaps you may have missed a nuance in the comments above yours? Nobody is claiming that heat pumps don't work, they certainly require a source of heat to pump though, and the air in a kitchen fridge ain't that.

Your comment in reply to: "Water heaters that are also AC units do exist"

https://www.homedepot.com/b/Plumbing-Water-Heaters-Tank-Wate...