I've bought a bunch of clothing in the past from Petco & Petsmart too in various sizes. Last month, we donated several items to a few pups in the care of rescues. Some of the rescue people shelter more than one at a time so clothing can get expensive.
I also tucked one of my business cards inside with a note to the Furever owner allowing them a choice of Tee shirt dresses from my shop. It's a small thing but it made me feel happy.