The title says it all: For the Answer Sandbox, there's no list of graduated answers (linked directly to the answers, not the questions.) While the Question Sandbox has a list of graduated answers, the Answer Sandbox answers can only be seen by higher-rep users. So should we post a community wiki answer and update it with previous answers?
No, there is no demand for it
There are currently 5 deleted posts, one of which was about undeleting an answer on Main. And the whole thread is 4.5 years old. There is on average about one draft per year in the answer Sandbox. There were discussions about abandoning the answer Sandbox because nobody uses it. It simply isn't worth it to keep the answer Sandbox in check because there is basically no activity. I think it can just sit around and if someone comes across it and wants to safe a draft there or get some feedback they can use it, but as long as the amount of posts in the answer sandbox doesn't ramp up a lot we should just leave everything as it is.