I am not sure how to answer your question effectively.

At my local Kroger (Smiths Food & Drug in Utah), the fixed value VGCs earn fuel points. That means they earn 2X in general.

They can earn 4x if they are included in a promotion.

However, sometimes the promotions are only for "restaurant/movie" gift cards. I have never tried buying a VGS at that time to see if they are included.