Name the additions.

Yes grsecurity offers actual hardening instead of touting snakeoil.

There is https://grsecurity.net/ but it's not free. It's developed by people with much more experience defending against attackers than all of the other projects combined.

No the closest alternative is https://grsecurity.net/

Denuvo does not need to hire from the scene. The scene is not some magical place full of uber leet crackers. People doing denuvo have the same or better skills.