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