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