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