They are absolutely zero-drop. What they refer to is the outsole “hugging” the heel on the outside to keep it in place.
For winter, I use the Wildling Northwolf which are similar but with wool (less rugged but more comfy) and for really cold, icy and snowy weather I use the Feelmax Kuuva 6.
I have other Vivobarefoot shoes (Gobi and Primus) and love them.