Hot Water System

Sure you can use one for 2 or 3 or how many you want. It is just matter of running pipes. We have one what goes to shower, toilet fauset and to kitchen.  There are million models so just get one that looks nice 🤣

Why not go solar?

We have solar heating which supplies our three bathrooms and the kitchen. It works exceptionally well and apart from the initial cost of installation, costs bugger all to use.

Our apartment in Q8 had 3 electric shower units  which cost an arm and a leg for electricity.

#4 - When I built our house, solar hot water was just coming onto the market and our builder declined to install it. Fortunately, my wife does not spend a long time in the shower, so we don't have big electricity bills.

Perhaps I could offer an alternative - don't have a hot water system.
We prefer cold showers so we simply didn't bother once we'd lift the cold mountainous area we used to live in.
32 degrees as normal here so a cold shower is very welcome.