Here is the full list of all 26 Warhammer: Vermintide 2 achievements. It takes around 120-150 hours to unlock all of the achievements on Windows.
Reach level 30 with Sienna
Reach Level 30 with all characters
Reach level 30 with Saltzpyre
Reach level 30 with Bardin
Complete Skittergate on Legend
Equip a Veteran Item
Reach level 30 with Kerillian
Complete Skittergate on Champion
Complete Prologue
Reach level 30 with Kruber
Unlock all Talent points for 1 career
Complete a level as every Hero
Craft 50 items
Equip Exotic items in every slot
Salvage 100 items
Complete Skittergate on Veteran
Complete Skittergate on Recruit
Complete Act 3
Craft an Item
Complete Act 2
Equip an Exotic Item
Salvage an item
Equip a Rare Item
Complete Act 1
Equip a Common Item
Unlock 1st Talent point