It seems incredibly unlikely that anyone is going to be able to do a active network scan of an address block to find devices with IPv6. Each end-user is granted

It seems incredibly unlikely that anyone is going to be able to do a active network scan of an address block to find devices with IPv6. Each end-user is granted a /64 network which has over 4 billion times the number of IPs than exist on the entire IPv4 internet. Even with MAC-based IPv6 autoconfiguration to reduce the number of IPs you have to scan using tables of assigned vendor prefixes, you still have a truly massive number of IPs to scan before you find anyone. Put another way, it would take over 500,000 years to just send an ICMPv6 packet to a /64 block (assuming you could even narrow it down to a /64 which itself seems just as unlikely) with a 1 Gbps connection (over ethernet).