What about home private network (for smart home, for example)?
Home networks don't usually have the problem of having to suddenly merge together with another, similarly-addressed network.
Nothing stops you getting a subnet allocated from your local RIR and announcing that on the internet, if you care about that sort of thing for your home network though. You just need a decent ISP.
> Nothing stops you […] You just need a decent ISP.
I’ll just leave that there.
No, I can’t just choose to have a decent ISP. I live in the real world where there’s only one choice where I live, same as a rather large majority of people in the world.
Sure, some network engineers will try and design v6 networks as though they're v4, but everyone else will just go and get a squillion addresses from the RIR that's unique to their org and then just use/announce that.