Comment #42069 on "HN doesn't understand the Internet Protocol". This opinion is frequently repeated here on HN but -- you CAN'T use IPv4 internally and expect to talk to external IPv6 hosts.
How would this IPv4 internal host (say 192.168.1.10) send a packet destined to 2001:db8::1? You can't stick a 128-bit IPv6 address into your IPv4 packet - there are only 32 bits available for the destination address inside its header.
NAT is not magic, it cannot extract a 128-bit number out of your 32-bit number.
Ironically, you are the one who needs to do more research.
I have deployed NAT64 in multiple networks before.
NAT64 is used when you have _internal_ IPv6 hosts who want to reach the _external_ IPv4 hosts. In order words, 2001:db8::1 can send something to 198.51.100.1 but not vice versa.
Your proposal is that we use IPv4 _internally_ since you think "internal IPv6 is overly complex" and we should "NAT to internal IPv4's". It doesn't exist since IPv4 is inherently forwards incompatible.
"HN doesn't understand the Internet Protocol" strikes again.
IPv6 internal network is simpler and probably a good idea for a brand-new network.
The big advantage is that don't have to worry about subnet size. No deciding how big subnet is going to be, and either making it too small and having to resize or making it too big and wasting space.
IPv6 is more complicated in that supports multiple addresses, but that is an advantage. For internal use, assign ULA addresses and route those over VPNs. For accessing Internet, computers use the ISP assigned addresses. Then assign fixed addresses from hosting provider to load balancers and external servers. This means that only Internet only sees random addresses; they know the provider but that is known with IPv4.
You ever ran out of ipv4 addresses on a home network? I find this probably does not apply to vast majority of users. And even if you do run out... If using DHCP is it trivial to change network prefix.
(Obligatory "anecdotal, but") I noticed that some routers have a very limited DHCP server, for example being limited to 100 simultaneously-connected devices only. Multi-tenant households with IoT devices may approach that number, the highest number I've seen is around 80 currently.
The S in IoT stands for security, of course. But it's going to be a bummer if my IoT devices forces me or my guests out of my network.
IPv6 can be made stateless with SLAAC so DHCP (and any DHCP-related limitations in the router) are completely out of the picture.
IPv6 from your ISP, fine, but once internal IPv6 is overly complex and unnecessary. Despite the claim to the contrary NAT is a feature, not bug.
The future for IPv6 is that Firewalls/Routers will handle IPv6 for the public addressees, then NAT to internal IPv4's.