Thats a good Idea for a plugin !
Although I havent tried to read what is returned by MarkdownRenderer.render() API, but I have used it a lot to render HTML of the part of Raw text I wanted to render inside any Modal or View. Since I am appending it inside the HTML DIV, so i believe it is returning HTML code. But You can try it if that works.
The only issue will be you will need to pass the parent MD file and the content yourself to the API. (Well, this could be even a feature, like the user can select a part of the content from the view, and then right click to get the HTML for the same and you can get that specific part as HTML inside the clipboard)
Check-out this post, on how to use it : I want to support some math notations,replace $$,$$ to \[, \] - #2 by Tu2_atmanand