It's useful though, as I think (correct me if I'm wrong) that the gases generally used in HVAC tends to have much worse warming effect than co2 per volume.

We do need heat pumps deployed at large scale, but sometimes I worry we don't understand they need to be handled with care at the end of their life

This has the useful property of being regulation-exempt because it's already literally everywhere. Unlike "F gases", which have much more serious greenhouse effects and are regulated in the UK (and elsewhere): https://www.gov.uk/government/collections/fluorinated-gas-f-...

You could install your own CO2-based heat pump in a way you wouldn't be allowed to do with a F-gas based one.

There is no reason not to use propane or butane, they have low global warming potential and is cheap. The fire risk is overstated, no one thinks twice about carrying a lighter in their pocket.

I heard CO2 is a gas with a powerful green house effect. What happens at the end of life of these units I wonder? What if they leak and it gets into the atmosphere!

There are resident systems, and they're of exactly the type listed in the article (i.e. water heaters). Residential... area heating pumps, so to say, are moving towards propane (afaik). I've been looking into getting a propane monoblock air-to-water pump, with an antifreeze loop towards an indoors heat exchanger / water tank.

CO2 does better with large temp deltas, like hot water tanks. Radiators don't produce large deltas - the inlet to outlet diff is typically under 10 degrees. But they run at higher pressures, making the manufacturing more expensive.