Hi, and welcome to the Quiltingboard. The loftiest poly I know of is Fatt Batt by Mountain Mist but it is nowhere near 1" thick, more like 1/2" which is about twice the thickness of Hobbs Poly down. I have used Fatt Batt for tied quilts but unless you do big stitch quilting I can't imagine how it is possible to get tiny hand quilting stitches with such a thick batting unless to quilt one stitch at a time (as opposed to rocking the needle and loading up to 8 stitches on the needle before pulling the thread through). I just tried searching for it on line and came up empty so it may be discontinued. Quilters Dream also makes a high loft poly called Dream Puff that is also 1/2" thick. I have never used this product from QD but I have loved every other batting of theirs that I have tried. While looking for the Fatt Batt I also stumbled on Fairfield Polyfil hi loft which is also described as being 1/2" thick. I have had mixed results with Fairfield battings, they tend to be an economy brand so I feel their quality is inconsistent. This is MHO and my experience only so your results may vary. Rather than buying her a roll, why not just buy a package of a couple different types to see what she likes.
Here is an amazon link to the fairfiled hi loft.
https://www.amazon.com/Fairfield-Pol...234406&sr=8-26
Edited to add there are very high loft polyester products intended for the upholstery industry, these are available in rolls only to my knowledge. I can't attest to how viable they are for quilting.