Answer, smile while you make a puppet.
Above, you see the single human foot in its two extreme poses from both inside and outside angles. The ankle flexes, the toes point and flex. Her metatarsal works when bent in place as if supporting the crouching weight of the character, (seen lower right below).
What you see of these characters is not made via armature movement exactly but rather by using expandable metal mesh as part of the make up of the layers of skin. So far it holds up to positioning over and over. It will likely fail during intense animating but the Halfland movement style is almost a montage and the few seconds of screen time can almost be tied down with wire to hold if need be.
Funny to think that all these hours and effort will only be shown for brief moments, scant seconds in the end. I don't feel badly about that, instead elated, as if the glimpses into this imaginary world are not quite there to be fully examined.
Thank you for watching.