I'm looking at a mini-tankless water heater that requires a flow rate of 0.53 GPM to turn on the heating element.

How much flow from a lav faucet is 0.53 GPM ?? Is that a fully opened tap, half open, or what?

I'm concerned that we usually don't turn on the tap enough to reach that flow rate; in which case a mini-tank would be what we want instead of the tankless.

And I've seen a few brand names mentioned here; what are some that I can investigate for their tank type (metal vs plastic) & other qualities to choose from ?

I also have to decide based on the amps required; I'm going to have to install a new electric cable from the fuse box and i'd like to run the smallest gauge i can get away with.