Here is the full list of all 50 Starfield achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Collect 10 Ships
Land on 100 Planets
Successfully Smuggle Contraband
Complete "One Giant Leap"
Reach Level 50
Complete "Unearthed"
Collect 20 Quantum Essence
Complete "Entangled"
Complete "In Their Footsteps"
Complete "High Price to Pay"
Complete "Further Into the Unknown"
Complete "Executive Level"
Complete "Guilty Parties"
Join Ryujin Industries
Complete "Legacy's End"
Complete "The Best There Is"
Complete "The Hammer Falls"
Reach Maximum Relationship Level with a Companion
Recruit 10 Separate Companions
Eliminate 300 Creatures
Mod 50 Weapons
Join the Crimson Fleet
Complete "Surgical Strike"
Produce 500 Total Resources from Outposts
Join the Freestar Rangers
Build an Outpost
Complete "All That Money Can Buy"
Eliminate 300 Human Enemies
Reach Level 25
Read 20 Skill Magazines
Complete 30 Terminal or Misc. Missions
Access 50 Computers
Visit 20 Star Systems
Complete "A Legacy Forged"
Complete "The Devils You Know"
Gather 500 Inorganic Resources
Bypass 50 Digital Locks
Complete 30 Activities
Join the UC Vanguard
Craft 100 Items
Complete "Into the Unknown"
Reach Level 10
Reach Level 5
Join Constellation
Modify a Ship
Enter Space for the First Time
Connect 5 Outposts with Cargo Links
Visit all Star Systems
Gather 500 Organic Resources
Reach Level 100