On paper internet exchanges (IX) are very simple in their implementation, simply put together a bunch of routers on a shared layer 2 ethernet switch (and coordinate IP addressing for the LAN) and…
There are several ways to map the IPv4 address space into the IPv6 address space, going right back to the first IPv6 addressing architecture RFC. Every compatibility protocol added a new one.
IPv6 added IPSEC which was backported to IPv4.
IPv6 tried to add easy renumbering, which did’t work and had to be discarded.
IPv6 added scoped addresses which are halfbaked and limited. Site-scoped addresses never worked and were discarded; link-scoped addresses are mostly used for autoconfiguration.
IPv6 added new autoconfiguration protocols instead of reusing bootp/DHCP.
The interface also allow to comment, post and interact with the original HN platform. Credentials are stored locally and are never sent to any server, you can check the source code here: https://github.com/GabrielePicco/hacker-news-rich.