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