I suspect Co-op does their own, or at least has someone do them to their own specifications, considering some of their offerings are extremely unique, such as one of the only PAO 0w-30 ILSAC rated PCMOs on the market, while relying solely on blends on conventionals for the rest of the PCMO line. I have no idea what their additive packages look like, though, offhand.
Yes, there are plenty of Co-op cardlocks, with a published guide. I don't know of any Esso or Shell ones outside the big bulk stations, but I do know of a couple Petro-Canada ones. I don't know how integrated their system is, though, in comparison to Co-op. Fuel station diesel prices at Husky aren't usually too bad, or any place within spitting distance of a Husky.