My favorite posthumous release that was pieced together (and not just a body of work previously made before death and released after death) is One of the Best Yet by Gang Starr. It's so crazy because none of the songs were made while Guru was alive. Most posthumous albums are full songs that mostly just need to have features added and be sequenced together.
The Gang Starr one was just random Guru verses that Preem needed to assemble beats for and make songs out of. For that reason, I was expecting it to be trash and Preem knocked it out the park.
The music nerd in me really would love to know the detailed process of how that and this new Mobb Deep album were made. When were certain verses made? What projects were they for? What stuff had to be changed, etc.