splityarn calls this the "Easiest Knitted Sweater Zipper Install Ever" and it looks like it might be. I haven't tried it yet but I'll let you know if I do - my one attempt to put a zipper into a knitted sweater came out OK, but not this nice.
Garment inspiration: An interesting, sleeveless cowl knit tube top one could wear with either end of the tube "up." It even has a halter-wear iteration. While labeled a DIY, it's just this series of s (Diy Ropa Patrones)