Handwashing only uses a small amount of water...I think I'd consider a small 4-6 gallon tank in each lavatory. Recovery rate is fairly slow, but should be plenty for hand washing unless it is something like a theater where there could be hundreds of people through quickly. These can be run off of 110vac. An electric tankless needs substantial power, then you have the losses to get it to the lavs, so people probably wouldn't get hot unless you add recirculation which adds even more to the complexity and cost. I'd keep it simple with a small tank in each lav, or maybe one, if they are back to back. Close to the point of use, so fast warm water.
Alternately, if I was going to use a tankless, I'd consider installing it in the bathroom, or nearby in a closet to minimize the response time to get hot water there.