We used them in the front-loader on the boat with no problems.
Just make sure you keep them stowed where teenagers can’t eat them.
That’s a great idea!
One of my relatives just rinses his clothes about half the time, and if he does use detergent, he pours in a very small amount.
He also cuts kitchen sponges into thirds or quarters, washes the dishes with bar soap or hand soap, and uses bar soap on his hair instead of shampoo.
I started cutting kitchen sponges myself because the smaller pieces work just as well, and I find them easier to maneuver. Plus we use the dishwasher machine for most dishes, so a smaller sponge lasts a decent amount of time.
The stores around here used to, but no longer carry powder pods - pods of dry concentrate. Were very convenient to pack for travel (as opposed to having to double-bag and seal liquid pods).