https://reverb.com/news/how-to-combine-2-daws-with-rewire this article lists the available hosts and slaves. It is a bit old so maybe changes are not noted and I notice melodyne is not listed. Found the article stating the advantages of using melodyne as a slave via rewire here https://music.tutsplus.com/tutorials/using-rewire-to-expand-your-audio-toolset--audio-1525
I used to rewire reaper inside of sonar to take advantage of certain free synths that were showing up in reaper due to its bridging certain 32 bit vsti that Sonar did not see. I was researching rewire uses and found this thread and should report that I see from my research that you can rewire into the stand alone version of melodyne and have more capability than using it inside sonar according to that article I read.