Xojo.IO.FolderItem.IsReadable
From Xojo Documentation
Read-Only Property (As Boolean )
This is True when you have permissions to read from the file or folder. In the case of a folder, it means you can read the contents of the folder.
Notes
Even if IsReadable is True, it does not provide a guarantee tha the read will succeed. If you want to read from a file, you should simply attempt to do so and handle any exceptions that may occur.