Those are just the same networking concepts as v4. Just 128 bits instead of 32. The hard thing can be ULA or SLAAC, which are like "yeah, just some random address to not get conflicts" and "yeah, first half your ISP gives you, second is taken from MAC address".

We even get rid of a bunch loaded crap that holepunching v4 and making it work developed through years.

Maybe it seems hard, because what was used before was not really learned how it works but just relied on hacks.