The Tesla heat pump is special not because of the heat pump but because of the octovalve.
When it's super cold, it will get its heat from the massive heat reservoir from the battery. For example if you stop supercharging, your battery will be in the 40-60C range. So even if it's -30 ouside, it doesn't matter.
If you're plugged home, you can preheat the battery from your app 30mins before you leave. That's energy stored in the form of heat in the battery additionally from the electrons. You just need 2-3 hours of heat stored anyway because you'll need to stop for supercharging and it will re-heat the battery.
When your car is parked and sun is shining, the car will heat the battery from the solar energy.
The only case is if the car is parked, cold (you haven't used it for 24 hours), not plugged in and it's been -21C for 24 hours you won't get any benefit from the heatpump.