It looks like WP-SEO do have built-in support for customizable og:type tag for individual post/page. The only thing missing is there is no UI offered to input the value.
I figured out that WPSEO_OpenGraph::type() looks for custom field named _yoast_wpseo_og_type. But, there is no way I could set the value. Is there anyway I could customize this for some of my pages?