To reach To reach the Hero Status (and the Achievement) you need to get past 150.000 Heroism Points, you get this Points for almost everything. I got Achievement at Mission 48, so you should’t worry about this to mutch. Here are short List with the things counts most:
– Building a Nuke: -50.000
– Disposing a Nuke: +1000
– Disposing ten Nukes: +30.000
– Complete a Missing with S-Rank: 1600
– Infiltrating FOBs: depends
– Most Achievements you unlock: 5000-50.000 Points
With the Hero Staus, you can infiltrate other Players FOB, who have built a Nuke. You can lose the Status (but ofc not the Achievement) by dropping below 100.000 Heroism Points.