SELinux made its public debut seventeen years ago, so it's not the best example of "recent" defensive work done by the NSA. ;)
To speak about SE for Android: I'm not sure how much weight I would lend to a few NSA employees helping Google/AOSP create SELinux profiles for Android. (It is recent work, though!)
I'm fairly certain that I would lend a lot of weight to public efforts to harden systems against the kinds of attacks that their TAO division launches.