This feature will be in 1.2.5, which is being submitted for review this week! I'm drafting this post early so that I can link it in the submission.

Open one of the following links, or try your favourite website. You can then use the 'Make a post' button in the popup or sidebar to generate a draft post with autofilled contents. Over time, we can customize how draft posts are generated for specific websites. Please comment below if you have thoughts on this feature.