DIY bags are one of the easiest projects.

Many people use a cozy to help re-hydrate food and to protect there pot in transit. Pretty easy to put together with a windshield sun shade and some heavy duty tape.

If you want a cloth sack, you could sew one out of silnylon pretty easily or contact a cottage manufacturer to see how much they would charge to sew it for you. https://blackwoodspress.com/blog/12378/cottage-backpacking-gear-directory/

This guy sells this one: https://www.shop.cookecustomsewing.com/product.sc?productId=226&categoryId=42

I'm not sure if it would fit your pot or he might be willing to modify it to your needs for a small fee.

edit... I've purchased from these guys before and was happy with my experience: https://liteaf.com/shop-1?olsPage=products%2Fround-bottom-pot-sack