Here is the full list of all 18 Sheltered achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Fully upgrade all systems
Fully upgrade a system
Have 5 or more plant stations in the shelter
Survive 100 days
Take the RV out on an expedition
Travel 1000 miles (cumulatively) on the map
Grow and harvest a plant from the plant station
Collect all 10 tools (on a single game)
Search 200 locations (cumulatively)
Subdue an enemy in combat
Travel 500 miles (cumulatively) on the map
Win combat using a gun
Trap an animal on the shelter surface
Travel 100 miles (cumulatively) on the map
Survive a week
Upgrade a system once
Craft your first object/item
Trap 100 animals on the shelter surface (cumulatively)