I’m not sure if anyone has composed an “ultimate list” detailing all of the unlockable cosmetics from the codes that come with toys and other merchandise. Regardless of how you might feel about buying random stuff for an in-game item, I hope we can all help each other figure out what each toy code unlocks. I know many of them might be self-explanatory, but some people might not realize this.
I’ve seen people in games have JFO and CQC helmets and different coatings, so please, if you know what merch gives what, drop it down below to help someone out. I don’t have much rn, but I hope we can get a good couple of contributions before this gets buried and forgotten.
I’ll do my best to edit this with updates if it gets enough traction. 
Northwest Sky armor coating - Found in blue/yellow MK VII Spartan funko pops
Watchdog armor coating - Reach max rank [SR 152] in Halo 5