The ground source heat pump works exactly the same as the fridge does. And the fridge is extracting heat from an approx. 40F heat source. So not much of a difference. The ground source heat pump will be pretty efficient if it's hitting deep and wet soil to get a good heat exchange.

But if we're comparing to resistive heating, an air-source heat pump near/below freezing points, propane or even natural gas, the economics move in favour of the electric fridge.