Powerful, "capable" plugins are obvious; NSA cannot stop people from writing them, and they have little reason to restrict their use.

I think what NSA is likely to keep confidential are in-house plugins that are so specialized and/or underengineered that their publication would give away confidential information: stolen and illegitimate secrets (e.g. cryptographic private keys from a game console SDK), or exploits that they intend to deny knowledge of and continue milking, or general strategies and methods (e.g. a tool to "customize" UEFI images, with the implication that they have means to install them on a victim's computer).