I have a CMS collection where we don't want to add an image to each item, however when trying to specify the OG image in the template settings I have no option to upload or specific an image URL, only select from a collection image, of which there are none.
Admin Note:
Currently we recommend setting an image field for Open Graph images for collections and binding that field in the Collection page settings.
An alternative solution would be to use custom code to specify a static Open Graph image for the collection page. See this Forum thread for more details ↗
Really need this feature as well. Unclear why the option is available for other page types and not collection pages.