I just had to google a bit to figure out how to copy files to/from an Ubuntu install on WSL2 so in case it’s useful to others
The windows drives are availble in the WSL environment as /mnt/drive letter
You can do open a windows explorer view on any WSL directory simply with
$ explorer.exe .
(specifying another directory that ‘.’ doesn’t seem to work, which I reported upstream as https://github.com/microsoft/WSL/issues/4297)
WSL paths are \wsl$ one for windows at the moment but they are looking at making them look nicer according to https://devblogs.microsoft.com/commandline/whats-new-for-wsl-in-windows-10-version-1903/