I used automotive touch up. They didn't have it listed on the site, but a call with a paint code and they were able to mix it.
I primarily use them because their rattle cans come with a colormatch guarantee. I'm not sure if their pens have that same match guarantee but worth to ask.
Application can be tricky because it's base and flake coats plus the clear. If you go with them go super light in the metallic flakes.