I have a heat pump heating and cooling my basement in Atlantic Canada.
Temperatures in the winter hold steady around -20C with some dips a few times in the -40c range when accounting for windchill.
Works just fine. I keep my basement a nice 21C. Heating works well. I see lots of disinfo posted online about heat pumps not working in the cold and it’s all horseshit. Make sure you’re buying a heat pump that’s built for colder temperatures and you’re golden.