This is more like smooth round rather than smooth floor, but maybe you can work with it: https://www.desmos.com/calculator/t8ev8mqdls a = number of steps b = sharpness it runs into problems with a "sharpness" value below 15.
Looking great man, my biggest crit is that the mouth looks far too sharp, he has no lips at all. It looks like someone cut through clay with a scalpel it has such a razor sharp edge.
Wherever you have a sharp edge in blender, there must also be a UV seam (but you don't need a sharp edge on every seam). Also, don't use the edge split modifier on the exported mesh (delete it before exporting). Just make sure to check "Smooth Groups" when you export as .obj (this will convert your sharp marked edges to…