I recite IPv6 addresses on my company networks from memory all the time. It helps that we got a bit lucky on our allocation. There are no letters.

Plus it's really easy to number subnets in a way that makes sense.

Yeah, no. If remote hosts could not send traffic to hosts behind NAT almost nothing would work.

The hacks employed to make NAT work make security worse, not better.

I did it by acquiring my own AS number and prefix, allowing me to set the geofeed, and announcing it via public BGP from a box in a data center. Took a few days for most things to pick it up the geolocation.