According to the following thread, hostPath volumes are not officially supported for wsl2, yet. They do suggest a workaround, though I had trouble getting it to work. I have found that prepending /run/desktop/mnt/host/c
seems to work for me.
// C:\someDir\volumeDir
hostPath:
path: /run/desktop/mnt/host/c/someDir/volumeDir
type: DirectoryOrCreate
Thread Source: https://github.com/docker/for-win/issues/5325
Suggested workaround from thread: https://github.com/docker/for-win/issues/5325#issuecomment-567594291