I use openwrt on my home network which uses dnsmasq for dhcp. It can give a static suffix which just works with the global prefix on the interface and the site local / ula prefix it uses

Indeed, that's correct ula usage, but shouldn't need nat rewriting. The global prefixes just need to be advertised by RA packets

Not sure on the history of that. It would make things like that easier

It certainly looks like you can give it a prefix to assign out, possibly even multiples

Address space is so huge that iirc the only global addresses in use are 2xxx::

Its so huge that it's not needed to use anything else is the goal as far as I see. If it starts with 2, it's global.

Ehh, I've seen both. Perhaps not in a home router context though, never really bothered to check

Point is, you should be able to have them have both. Or stick a reverse proxy in front that can translate. Unless they're somehow meant to be directly internet reachable the public addresses could be autogenerated

Full disclosure though I don't know anything about kubernetes.