XMPP is the closest social network in line with Richard Stallman’s vision of the internet. This instant message protocol, allows for you to easily host your own server, it’s fast and efficient, and has lots of different open source clients to choose from. Additionally, by making it extensible, it allows for anyone to build upon it to get their own desired features. This article goes over some of the basics of XMPP: https://simplifiedprivacy.com/xmpp-decentralized-signal-get-your-own-social-network/
Note: There are no affiliate links or sales text in this educational article discussing open source. Let’s discuss the technology and not attack the author.
No, not really, at least not by itself. IPv6 only makes NAT a tiny little easier/unnecessary, as every computer has a routeable IP address. However, many routers will block incoming connections by default, so you still have to go to your router config and fiddle, just as with NAT. IPv6 also doesn’t help with DNS, a routeable address by itself is meaningless when there is no means to find out what address the other guy has. IPv6 are dynamic and change all the time, even more frequently than IPv4.