I know it was discussed before the topic of window blinds, for privacy.
Here is my solution: a sheet of black crafting foam (from the craft store, used for cosplay costumes) of 5/8 thickness, cut to match the outline of the window sill, to cover the nuts from the window-holding screws. Then I punched holes to allow those nuts to fit through the foam. And done.
A fabric covering isn’t hard to sew. If I can do it (with the help of my daughter) then just about anyone can. I doubled up the fabric up so that the Peanuts characters are on both sides. Velcro holds the fabric wrapped around the metal door rod (the sewn-on mating pieces match up) and on the hinge side where adhesive back velcro is on the door and pieces are sewn at the top and bottom corners of the fabric.