How did you manage to get those achievements so quickly if you don't mind me asking?
Use BiLLzuMaNaTi guide which is now front page news. You should be able to complete the game in 2-3 hours. I’ve just got to finish it up now.
Complete Under No Flag War Story - Battlefield V
Attain 'Pioneer' status in Space Exploration - No Man's Sky
Attain 'Legend' status in Ships Destroyed - No Man's Sky