No it did not, it used Drawbridge OS research for Library OSes, which was integrated into Windows.

WSL 1.0 was a Drawbrige picoprocess.

Your confusion is natural among those that aren't into Windows programming.

Here are the links for the related information,

https://www.microsoft.com/en-us/research/project/drawbridge

WSL 1.0 architecture,

https://learn.microsoft.com/en-gb/archive/blogs/wsl/pico-pro...