After a query of the HTML documentation, I confirmed that you do not have an option to define where the dialog will open.
What you can define 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 a 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
And in C# you know some way?
– Danilo Pádua
In C already escapes from my knowledge, that deserves another question ;)
– Alan Rezende
Yes, in C# it is possible yes. Post in another question we will say how!
– Shura16