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