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