i got the answer about the Glycerin USP from shoppers

i contacted the RW packaging, and they said this:
Thank you for the inquiry. Yes as per the label claim, our Glycerine is 99% and is sourced from naturally occurring vegetable oils. It is gluten free and has no GMO.
The allergens, if there are any, are removed during processing.
Please feel free to contact us again if you have further questions.
Thank you and have a nice day.