In theory, IPv6 Privacy Extensions (https://datatracker.ietf.org/doc/html/rfc4941) could mitigate this. In practice, I imagine when you bind to `[::]:port`, that also means that the randomized addresses would work for new inbound connections, too. Not sure how long they typically last, but you'd be fighting against the clock at least before a new randomized address.

That being said, on a slightly less common note: it is quite possible to have each individual service running on a /128. E.g. on IPv6 k8s clusters, each pod can have a publicly addressable /128, so activities like NTP would require the container to have an NTP client in it to expose in that way. That'd mitigate a good chunk of information exposure -- that being said, I agree with the larger point about security via obscurity being insufficient.