Do you have PlayStation Plus? If so, this FAQ provides answers on the exclusive PS rewards and the limitations of cross-platform.
I Have PlayStation Plus. Why Can't I Buy Strikers?
If you have PlayStation Plus, every Striker current and future Striker will be unlocked and therefore Omega Strikers prevents you from purchasing the Strikers.
I Have PlayStation Plus. Why Aren't My Strikers Unlocked Across All Platforms?
Having all Strikers unlocked is a PlayStation Plus exclusive offer and not be available on other platforms such as Steam, mobile or other consoles.