How do I get my WebView2 exported app to run a second app in the subfolder of the main app?

I got this working with the Node web-kit extension and the Node Webkit export with no issues via:

But using the FileSystem extension, and exporting via WebView2 for windows, even though I confirmed at runtime that the app had desktop permissions, no matter what syntax or folder path style I've tried, it never tries to run the app.

Can anyone tell me what I'm doing wrong or how to do it right?

"<app>" should be used as the picker tag, not part of the path.