Geez, that’s a lot of projects. Granted, many were already open-source before MS got their hands on them, but still, a lot there.
Almost 20 years ago, there was an experimental IPv6 stack driver for NT4. It was released as an open-source driver by their R&D division, since they were at peak monopoly then...(coughcoughinternetexplorer4coughcough)
The documentation is still there if you look deep enough, but the code may well be long gone...
For Windows 2000/XP, the IPv6 stack became mature enough (and feature-complete by 2000, but only provisionally approved for production environments in 2001, fully so in 2006)—they just took it private...