Here is the full list of all 36 Valkyria Chronicles 4 achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Obtained all achievements.
Obtained all decorations.
Obtained all infantry weapons.
Watched all event scenes.
Obtained A ranks on all missions.
Obtained all tank parts.
Recruited all squad members.
Kept your promise with Riley Miller.
All of your classes were upgraded to max level.
Obtained all ship parts.
One of your classes was promoted to Paragon status.
Completed Chapter 18, and ended Belgar's dark ambitions.
Learned all orders.
Completed Chapter 17, and witnessed the end of the war.
Completed Chapter 15, and defeated both Walz and Crymaria.
Gave ship orders 15 times.
Triggered a Last Stand 15 times.
Completed Chapter 11, and made it past the Sea Fortress.
Gave orders 15 times.
Defeated 1000 enemy units.
Gave direct commands 15 times.
Earned 1,000,000 DCT cumulatively.
Defeated 15 enemy aces.
Developed the Hafen into a heavy tank.
One of your classes was promoted to Elite status.
Completed Chapter 7, and rendezvoused with the Centurion.
Rescued 10 allies in critical condition.
Obtained A ranks on 20 missions.
Completed Chapter 4, and won the battle of Siegval.
Completed a squad story for the first time.
One of your squadmates was promoted to Corporal.
Completed 10 missions without anyone in critical condition.
Defeated an enemy ace for the first time.
Learned an order at the Mess Hall for the first time.
Used R&D Facility for the first time.
Obtained an A rank on a mission for the first time.