I did a search on Amazon for "20mm quick release watch band". There I'm sure you'll find what you're looking for. I replaced the cheap looking band on mine with a much nicer silicone band that gives it a more sporty look . I got two for the wife for Xmas. One similar to the one I got and a nice leather one that she prefers to wear at work.
I went with the black/grey.
https://www.amazon.com/gp/product/B07346T99J/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1