Yarn subs?

I’m going to make a sweater and it calls for GGH Aspen, gauge of 12 st to 4" which I think counts as “bulky.” The majority of yarns I’ve found are wool or wool blends and the recipient says no.

Is is possible to double up on a worsted weight or DK weight to get bulky? Then my yarn options should increase.

Two strands of worsted weight yarn equals a bulky weight yarn.

Thank you! I was hoping that Knitpicks Shine would work.