DHCP does give you a globally unique IP address when your ISP has allocated a prefix to your router, that's how all the Internet-connected IPv6 devices get their addresses. Where is our misunderstanding?
For many of these systems, I don't control the user's router. I don't know how you imagine I'm supposed to create DNS records for each device when they're assigned some random IP address at some random network I don't control.
Have the device ping a central server and create randomword.centralserver.com, for example. However, if the problem is the DNS record, why has this thread been exclusively about globally routable IP addresses until now?
In https://news.ycombinator.com/item?id=45957048, addisonj suggested that the problem stems from the distinction from "local" and "global", and that with IPv6, you don't need that distinction.
That quite naturally flows into the question: okay, how are these devices supposed to get global IPv6 addresses then?
Yes, with IPv6, there are are enough addresses that you don't need to use NAT. All IPv6 devices that are connected to the internet have global IPv6 addresses. I don't quite understand the question here, it seems to me that we're asking "but how could we possibly do this entirely mundane everyday thing?".
Not all devices connected to the Internet have globally unique IPv6 addresses, SLAAC and often DHCPv6 makes local v6 addresses. Where's the globally unique IPv6 address supposed to be coming from?
For many of these systems, I don't control the user's router. I don't know how you imagine I'm supposed to create DNS records for each device when they're assigned some random IP address at some random network I don't control.