> Ultimately it's then GNU tools I'm after, the kernel isn't particularly interesting for my use cases.

That’s an interesting take, and it makes sense that some people need properly hybrid setups. I personally used Cygwin mostly to have access to a Linux dev environment inside Windows, not so much to apply GNU tools to Windows development. As a result I’m pretty happy with WSL just for the sake of having a Linux dev environment within easy reach, and I typically don’t feel a need to do much with the shared file system.