>exposing your LAN to public routing tables is madness

And I don't understand why people think that.

You are exposing a /64 network. That's 2^64 addresses, no one can scan your LAN if that's what you fear, nor can anyone reach your hosts if you build a stateful firewall that denies incoming connections - you know, just like NAT. But minus the packet modifications.

Using global addresses is not, of course, "exposing your LAN to public routing tables", or any charitable interpretation thereof. Reachability != addressing.

Is IPv6 Unique Local Addressing still a thing (or again)? Just because a machine has an IPv6 address does not mean it is automatically routable over the entire Internet.