We are two people and run the dishwasher every 2-3 days, but it’s really nice to go lazy and throw a pot or pan in there, along with a few plates. You’re not gonna get away with that if you go with the little dishwasher.
Also, you’re basically using the same amount of energy and water either way. Probably less for the larger one if you compare them full.
There’s something to be said for very early supernovae. I’m sure they’d all be giddy for something beyond 13 billion light-years (or whatever that works out to in red shift).
They make instant recirculation pumps that cycle the water through the tankless in a loop and stop when the hot water gets back to the pump. We have one. If you don’t already have the return pipes for it, you’d need some additional plumbing work. (Either way, it should be professionally installed).
It’s the same system you’d have for a tank, but it can’t run all the time, or it burns up the heater. You have to trigger it. They make flow switches, but mine (new construction) was cheesed. I just set up a zigbee switch with a 1 minute timer to trigger the pump.