Those things on Amazon are made of a hard foam and are for wearing only while painting the toenails.
I've never worn toe spreaders... and have great spread.
But I wear VFF's and have been wearing them for about 3 years... or a little more.
VFFs by design spread your toes because of the separation.
If you want your toes to spread to a more natural position... go barefoot.
This page explains a little about what a toe spreader does, however.
Joy-a-Toes Toe Spreaders
This is the one my friend who is addicted to high heels wears at night because her toes are crossing and crooked as hell and her doctor threatens her with surgery.