There made for flavoring food, really not for vaping.
You would be better off buying flavoring made specifically for e-juice .... It's really not expensive.
Technically ALL flavors are made for food, not vaping. GRAS (generally recognized as safe) is for eating or drinking, not inhaling. But that does not keep sellers from making you think the flavors are approved for vaping...but there is no such approval system with the FDA as yet.
And drug-store glycerin simply labeled as glycerin is PROBABLY made from plant oil (VG), but technically does not have to be. Beef and pork fat are also sources of glycerin, and allowed if it does not say otherwise. But chances are it is VG. That said, animal sourced glycerin is also fine to use, as long as it is USP.