Here is the full list of all 21 Jusant achievements. It takes around 5-6 hours to unlock all of the achievements on Windows.
Complete all cairns.
Complete the game.
Use the echo on a frozen ballast in Chapter 6.
Warm up the ballast in chapter 6.
Listen to all shells.
Turn all altars.
Read all of Bianca's journal entries.
Activate all frescos.
Read all letters.
Hug the ballast 20 times.
Restore your stamina more than 50 times while climbing.
Complete more than 200 jumps or double jumps in one game.
Stop 25 pebbles with a single echo from the ballast.
Place a piton at the top of a wall run.
Turn an altar.
Scare more than 10 chocos back to their burrow.
Hug the ballast.
Activate a fresco.
Complete a cairn.
Listen to a shell.
Read a letter.