After a query to the HTML documentation, I confirmed that you do not have an option to set where the dialog will open.
What you can set is the type of files that will be accepted with accept:
accept
If the value of the type attribute is file, this attribute indicates the types of files that the server accepts; otherwise it is ignored. The value must be the comma-separated list of unique content type specifiers:
A file extension starting with the STOP character (U + 002E). (E.g .: ".jpg, .png, .doc")
A valid MIME type with no extensions
audio / * representing sound files HTML5
video / * representing video files HTML5
image / * representing image files HTML5
Source: HTML Documentation