You can access them from the rest of the system. For normal usage the performance is completely acceptable but for development tasks it matters.
> Just copy it into the WSL file system
Yea bro totally. Totally. I'm gonna copy 2TB of media into the WSL virtual disk just so ffmpeg can run a little faster but still way slower than simply running linux.
(I beta tested the shit out of WSL1 and 2) before I wised up and just installed Gentoo forever.
People who run WSL are not normal users. The filesystem problems make Windows+WSL feel like a Trabant when you're used to a Porsche.