Hello Mike!

I have been using your wip-mingw-guile-2.2 branch for a while (great!)
and have some (~10) half-finished patches to run 8sync (non-blocking
sockets), pipes and other stuff that could be interesting, some of them
backported from guile master, see
https://gitlab.com/janneke/guile/-/commits/wip-mingw-guile-2.2

The past days I looked into the x86_64-w64-mingw32 cross-build in
Guix and created a patch, maybe you want to have a look at it.

Greetings,
Janneke