Of the 26 items in the Milestone section, three (near the bottom) are currently not done. All the rest are. (The last one should read "swim". And I hope that last one definitely happens!)
The first substantial commit (https://github.com/lundman/ZFSin/commit/6ea8093d48da0a0abc3b...) includes a large pile of code. It's clear this was (wisely) built out privately to begin with. I wonder how long it took to get to the above commit point.
While unrelated, thanks very much to the author for the TIL on how to do Windows kernel development! TIL about the free Windows VMs too.
I've opened https://github.com/lundman/ZFSin/issues/6 to hopefully prompt a license file to turn up.