“Most supmkts carry these “bricks” of bars of soap...”
I learned one of the big mistakes in a water shortage:
Don’t use the liquid soaps! It takes too much water to wash off. Same thing with detergent.
You are spot on about the bar soaps. Ivory is best. Not too much foam and slick to get off.
One item that is very, very handy is these stainless steel scrubbers. Kind of like stainless steel brillo pads without the soap. They come two to a pack and are pretty much indestructible.
Hmm. Learn something new every day. I don't use bar soaps because they make a mess, but it's easy enough to buy a couple of bars to keep for an emergency.