You might take a gander around Paramount's offerings (
https://www.paramount-3d.com/ ) as they have a wide range of colors, and IIRC they have Pantone numbers or RGB values or something listed.
I have found that their filament requires weird temperatures, particularly their PLA wants **** near ABS temperature. BUT they have colors I couldn't get elsewhere, like OD green and desert khaki for my military builds.