The point regarding the "unanswered" queue is a good one. It is indeed not ideal if questions appear as "answered" yet only have a partial answer.
However, considering the cost versus the benefit I think it is not likely that this will be implemented. Here, by cost I do not only mean the actual cost in developer-time but also the cost of added complexity ...
For myself, I would welcome such a button—without it, the main ways I can view unanswered questions are
visit Unanswered Questions, and find questions I've already seen in the recent questions list.
manually enter a page number into the URL which I hope will take me back far enough to see unfamiliar ones—which is laborious on mobile.
go to the final page, ...
There is no (term/phrase/name) for the (idea/object) you're describing
This one is for questions that are like "Here's this mathematical object. Is there a common name for such a thing?"
No, no such thing exists.
I'm posting this CW answer so that users who confidently concur that the answer to the question is "No" have an answer to vote on, and so ...
Yes, your thoughts/proof is correct
Because there are a bunch of proof-verification type questions where the OP's proof is absolutely correct, and users have said and upvoted this fact in the comments.
Yes, this is correct.
I'm posting this CW answer so that users who confidently concur have something to vote on, and so this question doesn't ...