I am using showSaveDirectoryPicker() in a client-side app and want to use the 'startIn' parameter so that the user does not have to work down through a large file system. Such as in the following:

const fileHandle = await self.showSaveDirectoryPicker({startIn: directoryHandle});

Without a directoryHandle for StartIn, showSaveDirectoryPicker() opens at the desktop or one of a few standard folders -- way at the top of a an often deep file structure.

The html input file element with the webkitdirectory is good for UPLOADING and is convenient because it opens in the client file system at the current place; that is, where the HTML file resides and is initiated from. How can I get a directoryHandle for that same place to use in DOWNLOADING using showSaveDirectoryPicker() ?