My router is behind the house NAT router which is behind the fiber NAT router so no, I do not have IPv6 connectivity. I think our delegated IPv6 subnet is not large enough.
Or possibly the IPv6 PD (Prefix Delegation) doesn't trickle down to the last router in the chain for whatever reason. There are some stingy ISPs, but the recommendation is to assign a /64 for the link between ISP and CPE and at least a /56 for the LAN.
Probably, but I remember checking and finding a smaller than recommended assignment.
IPv6 has been denied to me for so long now that I assume by default that I need to make my own arrangements. Back when AT&T started deliberately blocking IPv6 access, first at their border routers and then at their customer routers, I filed a complaint with the FCC who said it was fine.
So now I get IPv6 through a robust VPN service, rendering that traffic largely inscrutable and anonymous. If this makes things more difficult for the government, that is too bad; they made their choice.
And when the government rocks up with "give us DNS queries for this user over the last six months" they can simply go "no, we don't have that data". There's a difference between being able to deanonymize using large data sets and storing complete, detailed logs for the perusal of others.
What the court can do if the data exists at any point, is order that it be retained and given to law enforcement. The only way to prevent this is to not preserve it for any amount of time, and likely not even generate it.
There was a case where this came up a couple years ago where it was determined by the court that data which only exists ephemerally in DRAM may be subject to an order requiring it to be recorded and given to law enforcement.