So let's bring it back then:
Every internet address is really two parts β where to deliver, and who you are.
Normally the "who you are" part is just a number. This method builds it from your own key instead, so the address itself proves it's really yours. Like a tamper-proof name tag.
Here's the clever bit: routers only ever read the delivery part to move your data along. Your name tag is only checked at the very end, at the front door.
So you get an address that proves who you are, and it changes nothing about how the internet routes traffic.
Drop-in, no new rules.
Let's discuss this a little bit.
Every IPv6 GUA is two halves: a 64-bit routing prefix (handed to you by the network) and a 64-bit interface ID (your choice). CGA, and the BCA variant from nChain, make that suffix deterministic.
The IID = hash(public key, modifier, collision count, subnet prefix), truncated to 64 bits. The prefix is copied in verbatim. It's an input, never an output of the hash. So the routable half is always exactly what the network advertised.
Routing is longest-prefix-match on the leftmost bits. No router on the path ever reads the IID. It matters once, at the last hop, when ND maps the full /128 on the local link, and ND never leaves the wire.
So it's just a normal address inside an already-advertised prefix. No /128 host routes, no new BGP, DAD collision count handle uniqueness, RFC 7136 already made the IID opaque. A cryptographically generated suffix is invisible to internet routing rules.