There are several soaps that I used in the shower. The best ones I have used are Duke Cannon and Dr Bronner.
I have done the same with a bar of soap.I’ve had success using cream from the tube and just rubbing it on my face adding some water. Works in a pinch if you‘re without a brush.
My favorite brushless, inexpensive and works perfect...This looks very interesting. I never heard of it before. I'm surprised I never saw it mentioned on this forum before this.
I may have to try it.