FSF does not get in the way of security. FSF believes source code should be publicly available in order to even assume the software is secure or private. In a perfect world that would be nice. But in the real world, proprietary blobs are required to make the hardware functional. As long as OEMs are removed about open sourcing the firmwares, both GrapheneOS and GNU are right in their own way.
Yep. It was developed to improve parallelization and security of Firefox. Many core parts of Firefox have been replaced with Rust implementations.