Which AI can edit these photos?

Then you've still got the colors to play with. A flyer for handmade pottery could lean into earthy reds and warm yellows. You can use Flux for image-to-image editing here https://yesai.su/en/flux . Describe the background colors you want and tell it to keep the bowls' shapes and glaze patterns. Save a couple of versions so your sister can see how each one works with the flyer lettering.

The workbench itself can stay in the shot. For a pottery sale, showing where the pieces are made makes sense. I'd try Adobe Firefly for the object removal. Its Remove tool lets you brush over the buckets or brushes and fill that area back in.