It’s unlikely you’ll be able to find both the matching color and finish, especially if it’s enameled or vintage enamel paint. I would either strip and refinish or leave the chips as a part of its history. However, if you go to Hobby Lobby or some other craft store, they have enamel paints that are used for model trains and airplanes and things like that. They come in very small glass jars, so buy a few in the colors you’d need to mix to create your custom color. Get a piece of scrap metal and do some test swatches of your color combos and take notes about proportions. Be mindful that there are also different types, such as oil versus non-oil based which will have different finishes and adherence properties. I use the oil-based ones to paint glass when I don’t want to run my kiln and do the traditional stained glass painting process. Only the oil based ones stick to the glass. Also keep in mind that unless you are meticulous with sanding and a top coat to unify everything, the chipped area will always be somewhat visible even with a perfect color and finish (e.g. matte, gloss, semi-gloss, etc).

If you post a picture with good lighting (i.e. natural light source), I can give advice about color mixing if you’d like.