You mention IPv4. We're in 2024, this is getting ridiculous.
Governments should have done the same thing as with digital TV transition(s) : first ban selling devices that can't do IPv6, then ban selling (most) devices advertising they can do IPv4.
Here comes Matter protocol to the rescue, it supports IPv6 natively. It's even more complicated than Zigbee and of course doesn't specify all the devices available (but 1/4 of protocol specification is dedicated to smart fridge functionality because one fridge producer actually had someone to do any collaboration with protocol makers) and allows for "manufacturer specific fields" which means all manufacturers will have incompatible implementations of some fields anyway and you can't control them universally.
Governments should have done the same thing as with digital TV transition(s) : first ban selling devices that can't do IPv6, then ban selling (most) devices advertising they can do IPv4.