Here is the full list of all 26 Hitman GO: Definitive Edition achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Get chased by three guard dogs simultaneously.
Kill 100 enemies using the Silverballers.
Crush three enemies under a falling statue.
Kill 100 Pair (Grey) enemies.
Play for at least 100 turns in a single level.
Get pushed 100 steps.
Kill 100 Patrol (Yellow) enemies.
Complete all objectives in the first box.
Die at least 200 times.
Play for at least 5,000 turns.
Worn all three disguise types.
Kill 100 Turning (Teal) enemies.
Kill 100 Static (Blue) enemies.
Killed an enemy by emerging from a Secret Passage.
Play for at least 1,000 turns.
Kill 5 enemies at once.
Throw an object without alerting anyone.
Killed 2 enemies at once.
Complete all objectives in all chapters without using a single hint.
Complete all objectives in the second box.
Complete all objectives in the third box.
Used a hint, ignored the instructions but finished the level...
Complete all objectives in the fourth chapter.
Complete all objectives in the opera chapter.
Complete all objectives in the sixth chapter.
Complete all objectives in the St. Petersburg Stakeout Chapter.