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 the game.
Activate all frescos.
Listen to all shells.
Complete all cairns.
Use the echo on a frozen ballast in Chapter 6.
Warm up the ballast in chapter 6.
Turn all altars.
Read all of Bianca's journal entries.
Read all letters.
Stop 25 pebbles with a single echo from the ballast.
Complete more than 200 jumps or double jumps in one game.
Restore your stamina more than 50 times while climbing.
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 20 times.
Activate a fresco.
Hug the ballast.
Complete a cairn.
Listen to a shell.
Read a letter.